Avoid 'type mismatch' errors in ExtendedBeanInfo

Prior to this commit, ExtendedBeanInfo would add non-indexed write
methods without consideration for the presence of indexed read/write
methods, which is invalid per the JavaBeans spec and per the behavior
of java.beans.Introspector.  That is, a method with the signature

    void setFoo(Foo foo)

Should never be registered as a write method if the following method
signature is also present in the class

    void setFoo(int i, Foo foo)

In most cases, this oversight caused no problems, but in certain
situations where a bean actually contains such a mismatch of methods,
"type mismatch" errors were thrown when ExtendedBeanInfo attempted the
illegal addition against the underlying property descriptor.

The implementation is now more careful about checking the parameter type
of write methods -- if the property descriptor in question is an
IndexedPropertyDescriptor, i.e. has an indexed write method, then any
non-indexed write method candidate must have a single *array* parameter,
which conforms to the spec and to Introspector behavior.

Issue: SPR-8937

org.springframework.beans/src/main/java/org/springframework/beans/ExtendedBeanInfo.java

@@ -219,7 +219,9 @@ class ExtendedBeanInfo implements BeanInfo {
 					}
 				}
 				// update the existing descriptor's write method
-				if (writeMethod != null) {
+				if (writeMethod != null
+						&& !(existingPD instanceof IndexedPropertyDescriptor &&
+								!writeMethod.getParameterTypes()[0].isArray())) {
 					existingPD.setWriteMethod(writeMethod);
 				}
 

org.springframework.beans/src/test/java/org/springframework/beans/ExtendedBeanInfoTests.java

@@ -742,16 +742,28 @@ public class ExtendedBeanInfoTests {
 		assertThat(hasWriteMethodForProperty(ebi, "targetMethod"), is(false));
 	}
 
-	static class X {
-		public boolean isTargetMethod() {
-			return false;
+	@Test
+	public void cornerSpr8937() throws IntrospectionException {
+		@SuppressWarnings("unused") class A {
+			public void setAddress(String addr){ }
+			public void setAddress(int index, String addr) { }
+			public String getAddress(int index){ return null; }
+		}
+
+		{ // baseline. ExtendedBeanInfo needs to behave exactly like the following
+			BeanInfo bi = Introspector.getBeanInfo(A.class);
+			assertThat(hasReadMethodForProperty(bi, "address"), is(false));
+			assertThat(hasWriteMethodForProperty(bi, "address"), is(false));
+			assertThat(hasIndexedReadMethodForProperty(bi, "address"), is(true));
+			assertThat(hasIndexedWriteMethodForProperty(bi, "address"), is(true));
+		}
+		{
+			ExtendedBeanInfo bi = new ExtendedBeanInfo(Introspector.getBeanInfo(A.class));
+			assertThat(hasReadMethodForProperty(bi, "address"), is(false));
+			assertThat(hasWriteMethodForProperty(bi, "address"), is(false));
+			assertThat(hasIndexedReadMethodForProperty(bi, "address"), is(true));
+			assertThat(hasIndexedWriteMethodForProperty(bi, "address"), is(true));
 		}
 	}
 
-	static class Y extends X {
-		@Override
-		public boolean isTargetMethod() {
-			return false;
-		}
-	}
 }