Index: CHANGES.txt
===================================================================
--- CHANGES.txt	(revision 882977)
+++ CHANGES.txt	(working copy)
@@ -184,6 +184,9 @@
 * LUCENE-2013: SpanRegexQuery does not work with QueryScorer.
   (Benjamin Keil via Mark Miller)
 
+* LUCENE-2088: addAttribute() should only accept interfaces that
+  extend Attribute. (Shai Erera, Uwe Schindler)
+
 New features
 
 * LUCENE-1933: Provide a convenience AttributeFactory that creates a
Index: src/java/org/apache/lucene/util/AttributeSource.java
===================================================================
--- src/java/org/apache/lucene/util/AttributeSource.java	(revision 882918)
+++ src/java/org/apache/lucene/util/AttributeSource.java	(working copy)
@@ -224,6 +224,12 @@
   public <A extends Attribute> A addAttribute(Class<A> attClass) {
     AttributeImpl attImpl = attributes.get(attClass);
     if (attImpl == null) {
+      if (!(attClass.isInterface() && Attribute.class.isAssignableFrom(attClass))) {
+        throw new IllegalArgumentException(
+          "addAttribute() only accepts an interface that extends Attribute, but " +
+          attClass.getName() + " does not fulfil this contract."
+        );
+      }
       addAttributeImpl(attImpl = this.factory.createAttributeInstance(attClass));
     }
     return attClass.cast(attImpl);
Index: src/test/org/apache/lucene/util/TestAttributeSource.java
===================================================================
--- src/test/org/apache/lucene/util/TestAttributeSource.java	(revision 882918)
+++ src/test/org/apache/lucene/util/TestAttributeSource.java	(working copy)
@@ -141,4 +141,18 @@
     assertTrue("TypeAttribute is not implemented by TypeAttributeImpl",
       src.addAttribute(TypeAttribute.class) instanceof TypeAttributeImpl);
   }
+  
+  public void testInvalidArguments() throws Exception {
+    try {
+      AttributeSource src = new AttributeSource();
+      src.addAttribute(Token.class);
+      fail("Should throw IllegalArgumentException");
+    } catch (IllegalArgumentException iae) {}
+    
+    try {
+      AttributeSource src = new AttributeSource(Token.TOKEN_ATTRIBUTE_FACTORY);
+      src.addAttribute(Token.class);
+      fail("Should throw IllegalArgumentException");
+    } catch (IllegalArgumentException iae) {}
+  }
 }