Generic cleanup of warnings, whitespace and style.

By: Erik Broes <erikbroes@grum.nl>

paper-api/src/main/java/org/bukkit/configuration/InvalidConfigurationException.java

@@ -3,6 +3,7 @@ package org.bukkit.configuration;
 /**
  * Exception thrown when attempting to load an invalid {@link Configuration}
  */
+@SuppressWarnings("serial")
 public class InvalidConfigurationException extends Exception {
     /**
      * Creates a new instance of InvalidConfigurationException without a message or cause.