Added @DontExport annotation for telling Bukkit not to share a class …

…with another plugin

src/main/java/org/bukkit/plugin/java/JavaPluginLoader.java

@@ -27,6 +27,7 @@
 import org.bukkit.event.world.*;
 import org.bukkit.event.weather.*;
 import org.bukkit.plugin.*;
+import org.bukkit.plugin.java.annotations.DontExport;
 import org.yaml.snakeyaml.error.YAMLException;
 
 /**
@@ -217,7 +218,7 @@ public Class<?> getClassByName(final String name) {
     }
 
     public void setClass(final String name, final Class<?> clazz) {
-        if(!classes.containsKey(name)) {
+        if ((!classes.containsKey(name)) && (clazz.getAnnotation(DontExport.class) != null)) {
             classes.put(name, clazz);
         }
     }

src/main/java/org/bukkit/plugin/java/PluginClassLoader.java

@@ -28,7 +28,7 @@ protected Class<?> findClass(String name, boolean checkGlobal) throws ClassNotFo
         Class<?> result = classes.get(name);
 
         if (result == null) {
-            if(checkGlobal) {
+            if (checkGlobal) {
                 result = loader.getClassByName(name);
             }
 

src/main/java/org/bukkit/plugin/java/annotations/DontExport.java

@@ -0,0 +1,16 @@
+
+package org.bukkit.plugin.java.annotations;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Flags a class as private and not to be exported with other plugins
+ */
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface DontExport {
+
+}