Fix compile on JDK 8 and bad merge

proxy/src/main/java/com/velocitypowered/proxy/connection/client/ClientPlaySessionHandler.java

@@ -299,7 +299,6 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
     if (!spawned) {
       // Nothing special to do with regards to spawning the player
       spawned = true;
-      player.getConnection().delayedWrite(joinGame);
 
       destination.setActiveDimensionRegistry(joinGame.getDimensionRegistry()); // 1.16
       player.getConnection().delayedWrite(joinGame);

proxy/src/main/java/com/velocitypowered/proxy/connection/registry/DimensionData.java

@@ -48,14 +48,13 @@ public final class DimensionData {
                        @Nullable Long fixedTime, @Nullable Boolean createDragonFight) {
     Preconditions.checkNotNull(
             registryIdentifier, "registryIdentifier cannot be null");
-    Preconditions.checkArgument(registryIdentifier.length() > 0 && !registryIdentifier.isBlank(),
+    Preconditions.checkArgument(registryIdentifier.length() > 0,
             "registryIdentifier cannot be empty");
     Preconditions.checkArgument(logicalHeight >= 0, "localHeight must be >= 0");
     Preconditions.checkNotNull(
             burningBehaviourIdentifier, "burningBehaviourIdentifier cannot be null");
-    Preconditions.checkArgument(burningBehaviourIdentifier.length() > 0
-                    && !burningBehaviourIdentifier.isBlank(),
-            "burningBehaviourIdentifier cannot be empty");
+    Preconditions.checkArgument(burningBehaviourIdentifier.length() > 0,
+        "burningBehaviourIdentifier cannot be empty");
     this.registryIdentifier = registryIdentifier;
     this.isNatural = isNatural;
     this.ambientLight = ambientLight;

proxy/src/main/java/com/velocitypowered/proxy/connection/registry/DimensionInfo.java

@@ -21,12 +21,12 @@ public final class DimensionInfo {
     this.registryIdentifier = Preconditions.checkNotNull(
             registryIdentifier, "registryIdentifier cannot be null");
     Preconditions.checkArgument(
-            registryIdentifier.length() > 0 && !registryIdentifier.isBlank(),
+            registryIdentifier.length() > 0,
             "registryIdentifier cannot be empty");
     this.levelName = Preconditions.checkNotNull(
             levelName, "levelName cannot be null");
     Preconditions.checkArgument(
-            levelName.length() > 0 && !levelName.isBlank(),
+            levelName.length() > 0,
             "registryIdentifier cannot be empty");
     this.isFlat = isFlat;
     this.isDebugType = isDebugType;