Ignore non-prop 'set' methods in ExtendedBeanInfo

Previously, ExtendedBeanInfo would attempt to process methods named
exactly 'set'.  JavaBeans properties must have at least one character
following the 'set' prefix in order to qualify, and this is now
respected by EBI.

Thanks to Rob Winch for the patch fixing this problem.

Issue: SPR-8175

Author: cbeams

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

@@ -82,6 +82,9 @@ public ExtendedBeanInfo(BeanInfo delegate) throws IntrospectionException {
 			// is the method a NON-INDEXED setter? ignore return type in order to capture non-void signatures
 			if (method.getName().startsWith("set") && method.getParameterTypes().length == 1) {
 				String propertyName = propertyNameFor(method);
+				if(propertyName.length() == 0) {
+					continue ALL_METHODS;
+				}
 				for (PropertyDescriptor pd : delegate.getPropertyDescriptors()) {
 					Method readMethod = pd.getReadMethod();
 					Method writeMethod = pd.getWriteMethod();
@@ -109,6 +112,9 @@ public ExtendedBeanInfo(BeanInfo delegate) throws IntrospectionException {
 			// is the method an INDEXED setter? ignore return type in order to capture non-void signatures
 			if (method.getName().startsWith("set") && method.getParameterTypes().length == 2 && method.getParameterTypes()[0].equals(int.class)) {
 				String propertyName = propertyNameFor(method);
+				if(propertyName.length() == 0) {
+					continue ALL_METHODS;
+				}
 				DELEGATE_PD:
 				for (PropertyDescriptor pd : delegate.getPropertyDescriptors()) {
 					if (!(pd instanceof IndexedPropertyDescriptor)) {

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

@@ -19,8 +19,6 @@
 import static org.hamcrest.CoreMatchers.equalTo;
 import static org.hamcrest.CoreMatchers.instanceOf;
 import static org.hamcrest.CoreMatchers.is;
-import static org.hamcrest.CoreMatchers.notNullValue;
-import static org.hamcrest.CoreMatchers.nullValue;
 import static org.hamcrest.Matchers.greaterThan;
 import static org.hamcrest.Matchers.lessThan;
 import static org.junit.Assert.assertThat;
@@ -32,7 +30,6 @@
 import java.beans.Introspector;
 import java.beans.PropertyDescriptor;
 
-import org.junit.Ignore;
 import org.junit.Test;
 import org.springframework.beans.ExtendedBeanInfo.PropertyDescriptorComparator;
 
@@ -485,6 +482,23 @@ public void setFoo(String foo) { }
 		assertThat(hasWriteMethodForProperty(ebi, "foo"), is(true));
 	}
 
+	/**
+	 * Ensures that an empty string is not passed into a PropertyDescriptor constructor. This
+	 * could occur when handling ArrayList.set(int,Object)
+	 */
+	@Test
+	public void emptyPropertiesIgnored() throws IntrospectionException {
+		@SuppressWarnings("unused") class C {
+			public Object set(Object o) { return null; }
+			public Object set(int i, Object o) { return null; }
+		}
+
+		BeanInfo bi = Introspector.getBeanInfo(C.class);
+		ExtendedBeanInfo ebi = new ExtendedBeanInfo(bi);
+
+		assertThat(ebi.getPropertyDescriptors(), equalTo(bi.getPropertyDescriptors()));
+	}
+
 	@Test
 	public void propertyCountsMatch() throws IntrospectionException {
 		BeanInfo bi = Introspector.getBeanInfo(TestBean.class);
@@ -545,7 +559,6 @@ public void propertyDescriptorComparator() throws IntrospectionException {
 		assertThat(c.compare(new PropertyDescriptor("a", null, null), new PropertyDescriptor("A", null, null)), greaterThan(0));
 	}
 
-
 	private boolean hasWriteMethodForProperty(BeanInfo beanInfo, String propertyName) {
 		for (PropertyDescriptor pd : beanInfo.getPropertyDescriptors()) {
 			if (pd.getName().equals(propertyName)) {