Avoiding NPE when there is an ambiguous method and no method name has been provided.

org.springframework.integration/src/main/java/org/springframework/integration/handler/MethodInvokingMessageProcessor.java

@@ -200,6 +200,7 @@ public class MethodInvokingMessageProcessor implements MessageProcessor {
 					if (logger.isDebugEnabled()) {
 						logger.debug("Method [" + method + "] is not eligible for Message handling.", e);
 					}
+					return;
 				}
 				Class<?> targetParameterType = handlerMethod.getTargetParameterType();
 				if (matchesAnnotation || annotationType == null) {

org.springframework.integration/src/test/java/org/springframework/integration/message/PayloadAndHeaderMappingTests.java

@@ -470,6 +470,23 @@ public class PayloadAndHeaderMappingTests {
 		assertEquals(null, bean.lastHeaders.get("baz"));
 	}
 
+	@Test(expected = IllegalArgumentException.class)
+	public void twoStringsAmbiguousUsingMethodName() throws Exception {
+		SingleAmbiguousMethodTestBean bean = new SingleAmbiguousMethodTestBean();
+		new ServiceActivatingHandler(bean, "twoStrings");
+	}
+
+	@Test(expected = IllegalArgumentException.class)
+	public void twoStringsAmbiguousWithoutMethodName() throws Exception {
+		SingleAmbiguousMethodTestBean bean = new SingleAmbiguousMethodTestBean();
+		new ServiceActivatingHandler(bean);
+	}
+
+	@Test(expected = IllegalArgumentException.class)
+	public void twoStringsNoAnnotations() throws Exception {
+		this.getHandler("twoStringsNoAnnotations", String.class, String.class);
+	}
+
 	@Test(expected = IllegalArgumentException.class)
 	public void twoMapsNoAnnotationsAndObject() throws Exception {
 		this.getHandler("twoMapsNoAnnotationsAndObject", Map.class, Object.class, Map.class);
@@ -659,6 +676,14 @@ public class PayloadAndHeaderMappingTests {
 	}
 
 
+	@SuppressWarnings("unused")
+	private static class SingleAmbiguousMethodTestBean {
+
+		public String concat(String s1, String s2) {
+			return "s1" + "s2";
+		}
+	}
+
 	@SuppressWarnings({"unchecked", "unused"})
 	private static class TestBean {
 
@@ -762,6 +787,10 @@ public class PayloadAndHeaderMappingTests {
 			}
 		}
 
+		public void twoStringsNoAnnotations(String s1, String s2) {
+			// invalid due to ambiguity (no @Payload or @Headers)
+		}
+
 		public void twoMapsNoAnnotations(Map map1, Map<Object, Object> map2) {
 			// invalid due to ambiguity (no @Payload or @Headers)
 		}