Perform stronger early validation upon exported objects.

Author: broneill

src/main/java/org/cojen/dirmi/core/Engine.java

@@ -139,7 +139,7 @@ public Object export(Object name, Object obj) throws IOException {
 
         if (obj != null) {
             // Validate the remote object.
-            RemoteExaminer.remoteType(obj);
+            RemoteInfo.examine(RemoteExaminer.remoteType(obj));
         }
 
         mMainLock.lock();

src/main/java/org/cojen/dirmi/core/RemoteExaminer.java

@@ -25,17 +25,24 @@
  */
 final class RemoteExaminer {
     /**
-     * Returns the remote interface implemented by the given remote object.
+     * Returns the remote interface implemented by the given remote object, but doesn't fully
+     * validate it.
      *
      * @throws NullPointerException if object is null
-     * @throws IllegalArgumentException if object is malformed
+     * @throws IllegalArgumentException if more than one remote interface is defined, or if no
+     * remote interface is implemented at all
      */
     static Class<?> remoteType(Object obj) {
         return remoteTypeForClass(obj.getClass());
     }
 
     /**
-     * @throws IllegalArgumentException if object is null or malformed
+     * Returns the remote interface implemented by the given class, but doesn't fully validate
+     * it.
+     *
+     * @throws NullPointerException if clazz is null
+     * @throws IllegalArgumentException if more than one remote interface is defined, or if no
+     * remote interface is implemented at all
      */
     static Class<?> remoteTypeForClass(Class<?> clazz) {
         // Only consider the one that implements Remote.