Fixed AcquireSkillList related inconsistencies.

L2J_Mobius_01.0_Ertheia/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -681,7 +681,7 @@ public class SkillTreeData implements IXmlReader
 	 */
 	private Collection<SkillLearn> getAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -1491,7 +1491,7 @@ public class SkillTreeData implements IXmlReader
 	public Collection<SkillLearn> getNextAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;

L2J_Mobius_01.0_Ertheia/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -63,18 +63,20 @@ public class AcquireSkillList implements IClientOutgoingPacket
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(skill.getDualClassLevel());
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (ItemHolder item : skill.getRequiredItems())
 			{
 				packet.writeD(item.getId());
 				packet.writeQ(item.getCount());
 			}
-			final Collection<Skill> skillRem = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
+			
-			packet.writeC(skillRem.size());
+			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
-			for (Skill skillRemove : skillRem)
+			packet.writeC(removeSkills.size());
+			for (Skill removed : removeSkills)
 			{
-				packet.writeD(skillRemove.getId());
+				packet.writeD(removed.getId());
-				packet.writeH(skillRemove.getLevel());
+				packet.writeH(removed.getLevel());
 			}
 		}
 		return true;

L2J_Mobius_02.5_Underground/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -681,7 +681,7 @@ public class SkillTreeData implements IXmlReader
 	 */
 	private Collection<SkillLearn> getAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -1491,7 +1491,7 @@ public class SkillTreeData implements IXmlReader
 	public Collection<SkillLearn> getNextAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;

L2J_Mobius_02.5_Underground/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -59,22 +59,24 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		for (SkillLearn skill : _learnable)
 		{
 			packet.writeD(skill.getSkillId());
-			packet.writeD(skill.getSkillLevel());
+			packet.writeD(skill.getSkillLevel()); // Main writeD, Classic writeH.
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(skill.getDualClassLevel());
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (ItemHolder item : skill.getRequiredItems())
 			{
 				packet.writeD(item.getId());
 				packet.writeQ(item.getCount());
 			}
+			
 			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
 			packet.writeC(removeSkills.size());
 			for (Skill removed : removeSkills)
 			{
 				packet.writeD(removed.getId());
-				packet.writeD(removed.getLevel());
+				packet.writeD(removed.getLevel()); // Main writeD, Classic writeH.
 			}
 		}
 		return true;

L2J_Mobius_03.0_Helios/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -681,7 +681,7 @@ public class SkillTreeData implements IXmlReader
 	 */
 	private Collection<SkillLearn> getAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -1491,7 +1491,7 @@ public class SkillTreeData implements IXmlReader
 	public Collection<SkillLearn> getNextAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;

L2J_Mobius_03.0_Helios/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -59,22 +59,24 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		for (SkillLearn skill : _learnable)
 		{
 			packet.writeD(skill.getSkillId());
-			packet.writeD(skill.getSkillLevel());
+			packet.writeD(skill.getSkillLevel()); // Main writeD, Classic writeH.
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(skill.getDualClassLevel());
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (ItemHolder item : skill.getRequiredItems())
 			{
 				packet.writeD(item.getId());
 				packet.writeQ(item.getCount());
 			}
+			
 			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
 			packet.writeC(removeSkills.size());
 			for (Skill removed : removeSkills)
 			{
 				packet.writeD(removed.getId());
-				packet.writeD(removed.getLevel());
+				packet.writeD(removed.getLevel()); // Main writeD, Classic writeH.
 			}
 		}
 		return true;

L2J_Mobius_04.0_GrandCrusade/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -681,7 +681,7 @@ public class SkillTreeData implements IXmlReader
 	 */
 	private Collection<SkillLearn> getAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -1491,7 +1491,7 @@ public class SkillTreeData implements IXmlReader
 	public Collection<SkillLearn> getNextAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;

L2J_Mobius_04.0_GrandCrusade/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -59,22 +59,24 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		for (SkillLearn skill : _learnable)
 		{
 			packet.writeD(skill.getSkillId());
-			packet.writeD(skill.getSkillLevel());
+			packet.writeD(skill.getSkillLevel()); // Main writeD, Classic writeH.
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(skill.getDualClassLevel());
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (ItemHolder item : skill.getRequiredItems())
 			{
 				packet.writeD(item.getId());
 				packet.writeQ(item.getCount());
 			}
+			
 			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
 			packet.writeC(removeSkills.size());
 			for (Skill removed : removeSkills)
 			{
 				packet.writeD(removed.getId());
-				packet.writeD(removed.getLevel());
+				packet.writeD(removed.getLevel()); // Main writeD, Classic writeH.
 			}
 		}
 		return true;

L2J_Mobius_05.0_Salvation/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -681,7 +681,7 @@ public class SkillTreeData implements IXmlReader
 	 */
 	private Collection<SkillLearn> getAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -1491,7 +1491,7 @@ public class SkillTreeData implements IXmlReader
 	public Collection<SkillLearn> getNextAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;

L2J_Mobius_05.0_Salvation/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -59,23 +59,25 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		for (SkillLearn skill : _learnable)
 		{
 			packet.writeD(skill.getSkillId());
-			packet.writeD(skill.getSkillLevel());
+			packet.writeD(skill.getSkillLevel()); // Main writeD, Classic writeH.
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(skill.getDualClassLevel());
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0 : 1);
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (ItemHolder item : skill.getRequiredItems())
 			{
 				packet.writeD(item.getId());
 				packet.writeQ(item.getCount());
 			}
+			
 			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
 			packet.writeC(removeSkills.size());
 			for (Skill removed : removeSkills)
 			{
 				packet.writeD(removed.getId());
-				packet.writeD(removed.getLevel());
+				packet.writeD(removed.getLevel()); // Main writeD, Classic writeH.
 			}
 		}
 		return true;

L2J_Mobius_05.5_EtinasFate/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -681,7 +681,7 @@ public class SkillTreeData implements IXmlReader
 	 */
 	private Collection<SkillLearn> getAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -1491,7 +1491,7 @@ public class SkillTreeData implements IXmlReader
 	public Collection<SkillLearn> getNextAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;

L2J_Mobius_05.5_EtinasFate/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -59,23 +59,25 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		for (SkillLearn skill : _learnable)
 		{
 			packet.writeD(skill.getSkillId());
-			packet.writeD(skill.getSkillLevel());
+			packet.writeD(skill.getSkillLevel()); // Main writeD, Classic writeH.
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(skill.getDualClassLevel());
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0 : 1);
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (ItemHolder item : skill.getRequiredItems())
 			{
 				packet.writeD(item.getId());
 				packet.writeQ(item.getCount());
 			}
+			
 			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
 			packet.writeC(removeSkills.size());
 			for (Skill removed : removeSkills)
 			{
 				packet.writeD(removed.getId());
-				packet.writeD(removed.getLevel());
+				packet.writeD(removed.getLevel()); // Main writeD, Classic writeH.
 			}
 		}
 		return true;

L2J_Mobius_06.0_Fafurion/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -683,7 +683,7 @@ public class SkillTreeData implements IXmlReader
 	 */
 	private Collection<SkillLearn> getAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -1494,7 +1494,7 @@ public class SkillTreeData implements IXmlReader
 	public Collection<SkillLearn> getNextAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;

L2J_Mobius_06.0_Fafurion/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -59,23 +59,25 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		for (SkillLearn skill : _learnable)
 		{
 			packet.writeD(skill.getSkillId());
-			packet.writeD(skill.getSkillLevel());
+			packet.writeD(skill.getSkillLevel()); // Main writeD, Classic writeH.
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(skill.getDualClassLevel());
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0 : 1);
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (ItemHolder item : skill.getRequiredItems())
 			{
 				packet.writeD(item.getId());
 				packet.writeQ(item.getCount());
 			}
+			
 			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
 			packet.writeC(removeSkills.size());
 			for (Skill removed : removeSkills)
 			{
 				packet.writeD(removed.getId());
-				packet.writeD(removed.getLevel());
+				packet.writeD(removed.getLevel()); // Main writeD, Classic writeH.
 			}
 		}
 		return true;

L2J_Mobius_07.0_PreludeOfWar/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -683,7 +683,7 @@ public class SkillTreeData implements IXmlReader
 	 */
 	private Collection<SkillLearn> getAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -1494,7 +1494,7 @@ public class SkillTreeData implements IXmlReader
 	public Collection<SkillLearn> getNextAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;

L2J_Mobius_07.0_PreludeOfWar/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -59,23 +59,25 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		for (SkillLearn skill : _learnable)
 		{
 			packet.writeD(skill.getSkillId());
-			packet.writeD(skill.getSkillLevel());
+			packet.writeD(skill.getSkillLevel()); // Main writeD, Classic writeH.
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(skill.getDualClassLevel());
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0 : 1);
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (ItemHolder item : skill.getRequiredItems())
 			{
 				packet.writeD(item.getId());
 				packet.writeQ(item.getCount());
 			}
+			
 			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
 			packet.writeC(removeSkills.size());
 			for (Skill removed : removeSkills)
 			{
 				packet.writeD(removed.getId());
-				packet.writeD(removed.getLevel());
+				packet.writeD(removed.getLevel()); // Main writeD, Classic writeH.
 			}
 		}
 		return true;

L2J_Mobius_08.2_Homunculus/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -689,7 +689,7 @@ public class SkillTreeData implements IXmlReader
 	 */
 	private Collection<SkillLearn> getAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -1500,7 +1500,7 @@ public class SkillTreeData implements IXmlReader
 	public Collection<SkillLearn> getNextAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;

L2J_Mobius_08.2_Homunculus/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -60,23 +60,25 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		for (SkillLearn skill : _learnable)
 		{
 			packet.writeD(skill.getSkillId());
-			packet.writeD(skill.getSkillLevel());
+			packet.writeD(skill.getSkillLevel()); // Main writeD, Essence writeH.
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(skill.getDualClassLevel());
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0 : 1);
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (List<ItemHolder> item : skill.getRequiredItems())
 			{
 				packet.writeD(item.get(0).getId());
 				packet.writeQ(item.get(0).getCount());
 			}
+			
 			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
 			packet.writeC(removeSkills.size());
 			for (Skill removed : removeSkills)
 			{
 				packet.writeD(removed.getId());
-				packet.writeD(removed.getLevel());
+				packet.writeD(removed.getLevel()); // Main writeD, Essence writeH.
 			}
 		}
 		return true;

L2J_Mobius_09.2_ReturnOfTheQueenAnt/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -689,7 +689,7 @@ public class SkillTreeData implements IXmlReader
 	 */
 	private Collection<SkillLearn> getAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -1500,7 +1500,7 @@ public class SkillTreeData implements IXmlReader
 	public Collection<SkillLearn> getNextAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;

L2J_Mobius_09.2_ReturnOfTheQueenAnt/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -60,23 +60,25 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		for (SkillLearn skill : _learnable)
 		{
 			packet.writeD(skill.getSkillId());
-			packet.writeD(skill.getSkillLevel());
+			packet.writeD(skill.getSkillLevel()); // Main writeD, Essence writeH.
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(skill.getDualClassLevel());
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0 : 1);
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (List<ItemHolder> item : skill.getRequiredItems())
 			{
 				packet.writeD(item.get(0).getId());
 				packet.writeQ(item.get(0).getCount());
 			}
+			
 			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
 			packet.writeC(removeSkills.size());
 			for (Skill removed : removeSkills)
 			{
 				packet.writeD(removed.getId());
-				packet.writeD(removed.getLevel());
+				packet.writeD(removed.getLevel()); // Main writeD, Essence writeH.
 			}
 		}
 		return true;

L2J_Mobius_10.1_MasterClass/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -689,7 +689,7 @@ public class SkillTreeData implements IXmlReader
 	 */
 	private Collection<SkillLearn> getAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -1500,7 +1500,7 @@ public class SkillTreeData implements IXmlReader
 	public Collection<SkillLearn> getNextAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;

L2J_Mobius_10.1_MasterClass/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -60,23 +60,25 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		for (SkillLearn skill : _learnable)
 		{
 			packet.writeD(skill.getSkillId());
-			packet.writeD(skill.getSkillLevel());
+			packet.writeD(skill.getSkillLevel()); // Main writeD, Essence writeH.
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(skill.getDualClassLevel());
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0 : 1);
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (List<ItemHolder> item : skill.getRequiredItems())
 			{
 				packet.writeD(item.get(0).getId());
 				packet.writeQ(item.get(0).getCount());
 			}
+			
 			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
 			packet.writeC(removeSkills.size());
 			for (Skill removed : removeSkills)
 			{
 				packet.writeD(removed.getId());
-				packet.writeD(removed.getLevel());
+				packet.writeD(removed.getLevel()); // Main writeD, Essence writeH.
 			}
 		}
 		return true;

L2J_Mobius_10.2_MasterClass/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -689,7 +689,7 @@ public class SkillTreeData implements IXmlReader
 	 */
 	private Collection<SkillLearn> getAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -1500,7 +1500,7 @@ public class SkillTreeData implements IXmlReader
 	public Collection<SkillLearn> getNextAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;

L2J_Mobius_10.2_MasterClass/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -60,23 +60,25 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		for (SkillLearn skill : _learnable)
 		{
 			packet.writeD(skill.getSkillId());
-			packet.writeD(skill.getSkillLevel());
+			packet.writeD(skill.getSkillLevel()); // Main writeD, Essence writeH.
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(skill.getDualClassLevel());
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0 : 1);
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (List<ItemHolder> item : skill.getRequiredItems())
 			{
 				packet.writeD(item.get(0).getId());
 				packet.writeQ(item.get(0).getCount());
 			}
+			
 			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
 			packet.writeC(removeSkills.size());
 			for (Skill removed : removeSkills)
 			{
 				packet.writeD(removed.getId());
-				packet.writeD(removed.getLevel());
+				packet.writeD(removed.getLevel()); // Main writeD, Essence writeH.
 			}
 		}
 		return true;

L2J_Mobius_Classic_2.0_Saviors/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -680,7 +680,7 @@ public class SkillTreeData implements IXmlReader
 	 */
 	private Collection<SkillLearn> getAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -1456,7 +1456,7 @@ public class SkillTreeData implements IXmlReader
 	public Collection<SkillLearn> getNextAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;

L2J_Mobius_Classic_2.0_Saviors/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -59,22 +59,24 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		for (SkillLearn skill : _learnable)
 		{
 			packet.writeD(skill.getSkillId());
-			packet.writeH(skill.getSkillLevel());
+			packet.writeH(skill.getSkillLevel()); // Main writeD, Classic writeH.
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(0); // Skill dual class level.
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (ItemHolder item : skill.getRequiredItems())
 			{
 				packet.writeD(item.getId());
 				packet.writeQ(item.getCount());
 			}
+			
 			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
 			packet.writeC(removeSkills.size());
 			for (Skill removed : removeSkills)
 			{
 				packet.writeD(removed.getId());
-				packet.writeD(removed.getLevel());
+				packet.writeH(removed.getLevel()); // Main writeD, Classic writeH.
 			}
 		}
 		return true;

L2J_Mobius_Classic_2.1_Zaken/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -680,7 +680,7 @@ public class SkillTreeData implements IXmlReader
 	 */
 	private Collection<SkillLearn> getAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -1456,7 +1456,7 @@ public class SkillTreeData implements IXmlReader
 	public Collection<SkillLearn> getNextAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;

L2J_Mobius_Classic_2.1_Zaken/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -59,22 +59,24 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		for (SkillLearn skill : _learnable)
 		{
 			packet.writeD(skill.getSkillId());
-			packet.writeH(skill.getSkillLevel());
+			packet.writeH(skill.getSkillLevel()); // Main writeD, Classic writeH.
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(0); // Skill dual class level.
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (ItemHolder item : skill.getRequiredItems())
 			{
 				packet.writeD(item.getId());
 				packet.writeQ(item.getCount());
 			}
+			
 			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
 			packet.writeC(removeSkills.size());
 			for (Skill removed : removeSkills)
 			{
 				packet.writeD(removed.getId());
-				packet.writeD(removed.getLevel());
+				packet.writeH(removed.getLevel()); // Main writeD, Classic writeH.
 			}
 		}
 		return true;

L2J_Mobius_Classic_2.2_Antharas/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -680,7 +680,7 @@ public class SkillTreeData implements IXmlReader
 	 */
 	private Collection<SkillLearn> getAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -1456,7 +1456,7 @@ public class SkillTreeData implements IXmlReader
 	public Collection<SkillLearn> getNextAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;

L2J_Mobius_Classic_2.2_Antharas/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -59,23 +59,25 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		for (SkillLearn skill : _learnable)
 		{
 			packet.writeD(skill.getSkillId());
-			packet.writeH(skill.getSkillLevel());
+			packet.writeH(skill.getSkillLevel()); // Main writeD, Classic writeH.
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(0); // Skill dual class level.
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0 : 1);
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (ItemHolder item : skill.getRequiredItems())
 			{
 				packet.writeD(item.getId());
 				packet.writeQ(item.getCount());
 			}
+			
 			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
 			packet.writeC(removeSkills.size());
 			for (Skill removed : removeSkills)
 			{
 				packet.writeD(removed.getId());
-				packet.writeD(removed.getLevel());
+				packet.writeH(removed.getLevel()); // Main writeD, Classic writeH.
 			}
 		}
 		return true;

L2J_Mobius_Classic_2.3_SevenSigns/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -680,7 +680,7 @@ public class SkillTreeData implements IXmlReader
 	 */
 	private Collection<SkillLearn> getAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -1456,7 +1456,7 @@ public class SkillTreeData implements IXmlReader
 	public Collection<SkillLearn> getNextAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;

L2J_Mobius_Classic_2.3_SevenSigns/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -59,23 +59,25 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		for (SkillLearn skill : _learnable)
 		{
 			packet.writeD(skill.getSkillId());
-			packet.writeH(skill.getSkillLevel());
+			packet.writeH(skill.getSkillLevel()); // Main writeD, Classic writeH.
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(0); // Skill dual class level.
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0 : 1);
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (ItemHolder item : skill.getRequiredItems())
 			{
 				packet.writeD(item.getId());
 				packet.writeQ(item.getCount());
 			}
+			
 			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
 			packet.writeC(removeSkills.size());
 			for (Skill removed : removeSkills)
 			{
 				packet.writeD(removed.getId());
-				packet.writeD(removed.getLevel());
+				packet.writeH(removed.getLevel()); // Main writeD, Classic writeH.
 			}
 		}
 		return true;

L2J_Mobius_Classic_2.4_SecretOfEmpire/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -680,7 +680,7 @@ public class SkillTreeData implements IXmlReader
 	 */
 	private Collection<SkillLearn> getAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -1456,7 +1456,7 @@ public class SkillTreeData implements IXmlReader
 	public Collection<SkillLearn> getNextAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;

L2J_Mobius_Classic_2.4_SecretOfEmpire/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -59,23 +59,25 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		for (SkillLearn skill : _learnable)
 		{
 			packet.writeD(skill.getSkillId());
-			packet.writeH(skill.getSkillLevel());
+			packet.writeH(skill.getSkillLevel()); // Main writeD, Classic writeH.
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(0); // Skill dual class level.
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0 : 1);
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (ItemHolder item : skill.getRequiredItems())
 			{
 				packet.writeD(item.getId());
 				packet.writeQ(item.getCount());
 			}
+			
 			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
 			packet.writeC(removeSkills.size());
 			for (Skill removed : removeSkills)
 			{
 				packet.writeD(removed.getId());
-				packet.writeD(removed.getLevel());
+				packet.writeH(removed.getLevel()); // Main writeD, Classic writeH.
 			}
 		}
 		return true;

L2J_Mobius_Classic_3.0_TheKamael/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -680,7 +680,7 @@ public class SkillTreeData implements IXmlReader
 	 */
 	private Collection<SkillLearn> getAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -1456,7 +1456,7 @@ public class SkillTreeData implements IXmlReader
 	public Collection<SkillLearn> getNextAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;

L2J_Mobius_Classic_3.0_TheKamael/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -59,23 +59,25 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		for (SkillLearn skill : _learnable)
 		{
 			packet.writeD(skill.getSkillId());
-			packet.writeH(skill.getSkillLevel());
+			packet.writeH(skill.getSkillLevel()); // Main writeD, Classic writeH.
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(0); // Skill dual class level.
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0 : 1);
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (ItemHolder item : skill.getRequiredItems())
 			{
 				packet.writeD(item.getId());
 				packet.writeQ(item.getCount());
 			}
+			
 			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
 			packet.writeC(removeSkills.size());
 			for (Skill removed : removeSkills)
 			{
 				packet.writeD(removed.getId());
-				packet.writeD(removed.getLevel());
+				packet.writeH(removed.getLevel()); // Main writeD, Classic writeH.
 			}
 		}
 		return true;

L2J_Mobius_Classic_Interlude/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -680,7 +680,7 @@ public class SkillTreeData implements IXmlReader
 	 */
 	private Collection<SkillLearn> getAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -1456,7 +1456,7 @@ public class SkillTreeData implements IXmlReader
 	public Collection<SkillLearn> getNextAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;

L2J_Mobius_Classic_Interlude/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -59,22 +59,24 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		for (SkillLearn skill : _learnable)
 		{
 			packet.writeD(skill.getSkillId());
-			packet.writeH(skill.getSkillLevel());
+			packet.writeH(skill.getSkillLevel()); // Main writeD, Classic writeH.
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(0); // Skill dual class level.
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (ItemHolder item : skill.getRequiredItems())
 			{
 				packet.writeD(item.getId());
 				packet.writeQ(item.getCount());
 			}
+			
 			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
 			packet.writeC(removeSkills.size());
 			for (Skill removed : removeSkills)
 			{
 				packet.writeD(removed.getId());
-				packet.writeD(removed.getLevel());
+				packet.writeH(removed.getLevel()); // Main writeD, Classic writeH.
 			}
 		}
 		return true;

L2J_Mobius_Essence_4.2_DwellingOfSpirits/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -686,7 +686,7 @@ public class SkillTreeData implements IXmlReader
 	 */
 	private Collection<SkillLearn> getAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -1462,7 +1462,7 @@ public class SkillTreeData implements IXmlReader
 	public Collection<SkillLearn> getNextAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;

L2J_Mobius_Essence_4.2_DwellingOfSpirits/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -60,23 +60,25 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		for (SkillLearn skill : _learnable)
 		{
 			packet.writeD(skill.getSkillId());
-			packet.writeH(skill.getSkillLevel());
+			packet.writeH(skill.getSkillLevel()); // Main writeD, Essence writeH.
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(0); // Skill dual class level.
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0 : 1);
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (List<ItemHolder> item : skill.getRequiredItems())
 			{
 				packet.writeD(item.get(0).getId());
 				packet.writeQ(item.get(0).getCount());
 			}
+			
 			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
 			packet.writeC(removeSkills.size());
 			for (Skill removed : removeSkills)
 			{
 				packet.writeD(removed.getId());
-				packet.writeD(removed.getLevel());
+				packet.writeH(removed.getLevel()); // Main writeD, Essence writeH.
 			}
 		}
 		return true;

L2J_Mobius_Essence_5.2_FrostLord/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -686,7 +686,7 @@ public class SkillTreeData implements IXmlReader
 	 */
 	private Collection<SkillLearn> getAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -1462,7 +1462,7 @@ public class SkillTreeData implements IXmlReader
 	public Collection<SkillLearn> getNextAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;

L2J_Mobius_Essence_5.2_FrostLord/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -60,23 +60,25 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		for (SkillLearn skill : _learnable)
 		{
 			packet.writeD(skill.getSkillId());
-			packet.writeH(skill.getSkillLevel());
+			packet.writeH(skill.getSkillLevel()); // Main writeD, Essence writeH.
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(0); // Skill dual class level.
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0 : 1);
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (List<ItemHolder> item : skill.getRequiredItems())
 			{
 				packet.writeD(item.get(0).getId());
 				packet.writeQ(item.get(0).getCount());
 			}
+			
 			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
 			packet.writeC(removeSkills.size());
 			for (Skill removed : removeSkills)
 			{
 				packet.writeD(removed.getId());
-				packet.writeD(removed.getLevel());
+				packet.writeH(removed.getLevel()); // Main writeD, Essence writeH.
 			}
 		}
 		return true;

L2J_Mobius_Essence_6.1_BattleChronicle/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -686,7 +686,7 @@ public class SkillTreeData implements IXmlReader
 	 */
 	private Collection<SkillLearn> getAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -1462,7 +1462,7 @@ public class SkillTreeData implements IXmlReader
 	public Collection<SkillLearn> getNextAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;

L2J_Mobius_Essence_6.1_BattleChronicle/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -60,23 +60,25 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		for (SkillLearn skill : _learnable)
 		{
 			packet.writeD(skill.getSkillId());
-			packet.writeH(skill.getSkillLevel());
+			packet.writeH(skill.getSkillLevel()); // Main writeD, Essence writeH.
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(0); // Skill dual class level.
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0 : 1);
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (List<ItemHolder> item : skill.getRequiredItems())
 			{
 				packet.writeD(item.get(0).getId());
 				packet.writeQ(item.get(0).getCount());
 			}
+			
 			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
 			packet.writeC(removeSkills.size());
 			for (Skill removed : removeSkills)
 			{
 				packet.writeD(removed.getId());
-				packet.writeD(removed.getLevel());
+				packet.writeH(removed.getLevel()); // Main writeD, Essence writeH.
 			}
 		}
 		return true;

L2J_Mobius_Essence_6.2_Vanguard/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -686,7 +686,7 @@ public class SkillTreeData implements IXmlReader
 	 */
 	private Collection<SkillLearn> getAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -1462,7 +1462,7 @@ public class SkillTreeData implements IXmlReader
 	public Collection<SkillLearn> getNextAvailableSkills(Player player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
+		final Set<SkillLearn> result = new HashSet<>();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;

L2J_Mobius_Essence_6.2_Vanguard/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -60,23 +60,25 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		for (SkillLearn skill : _learnable)
 		{
 			packet.writeD(skill.getSkillId());
-			packet.writeH(skill.getSkillLevel());
+			packet.writeH(skill.getSkillLevel()); // Main writeD, Essence writeH.
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(0); // Skill dual class level.
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0 : 1);
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (List<ItemHolder> item : skill.getRequiredItems())
 			{
 				packet.writeD(item.get(0).getId());
 				packet.writeQ(item.get(0).getCount());
 			}
+			
 			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
 			packet.writeC(removeSkills.size());
 			for (Skill removed : removeSkills)
 			{
 				packet.writeD(removed.getId());
-				packet.writeD(removed.getLevel());
+				packet.writeH(removed.getLevel()); // Main writeD, Essence writeH.
 			}
 		}
 		return true;