Add check for existing config file. Addresses BUKKIT-1851

By: Wesley Wolfe <weswolf@aol.com>

paper-api/src/main/java/org/bukkit/plugin/Plugin.java

@@ -58,6 +58,7 @@ public interface Plugin extends CommandExecutor {
     /**
      * Saves the raw contents of the default config.yml file to the location retrievable by {@link #getConfig()}.
      * If there is no default config.yml embedded in the plugin, an empty config.yml file is saved.
+     * This should fail silently if the config.yml already exists.
      */
     public void saveDefaultConfig();
 

paper-api/src/main/java/org/bukkit/plugin/java/JavaPlugin.java

@@ -133,7 +133,9 @@ public abstract class JavaPlugin extends PluginBase {
     }
 
     public void saveDefaultConfig() {
-        saveResource("config.yml", false);
+        if (!new File(getDataFolder(), "config.yml").exists()) {
+            saveResource("config.yml", false);
+        }
     }
 
     public void saveResource(String resourcePath, boolean replace) {