Add ResolvableTypeProvider

Provide a mean to detect the actual ResolvableType based on a instance as
a counter measure to type erasure.

Upgrade the event infrastructure to detect if the event (or the payload)
implements such interface. When this is the case, the return value of
`getResolvableType` is used to validate its generic type against the
method signature of the listener.

Issue: SPR-13069

spring-core/src/test/java/org/springframework/core/ResolvableTypeTests.java

@@ -133,6 +133,34 @@ public class ResolvableTypeTests {
 		assertTrue(type.isAssignableFrom(String.class));
 	}
 
+	@Test
+	public void forInstanceMustNotBeNull() {
+		this.thrown.expect(IllegalArgumentException.class);
+		this.thrown.expectMessage("Instance must not be null");
+		ResolvableType.forInstance(null);
+	}
+
+	@Test
+	public void forInstanceNoProvider() {
+		ResolvableType type = ResolvableType.forInstance(new Object());
+		assertThat(type.getType(), equalTo(Object.class));
+		assertThat(type.resolve(), equalTo(Object.class));
+	}
+
+	@Test
+	public void forInstanceProvider() {
+		ResolvableType type = ResolvableType.forInstance(new MyGenericInterfaceType<String>(String.class));
+		assertThat(type.getRawClass(), equalTo(MyGenericInterfaceType.class));
+		assertThat(type.getGeneric().resolve(), equalTo(String.class));
+	}
+
+	@Test
+	public void forInstanceProviderNull() {
+		ResolvableType type = ResolvableType.forInstance(new MyGenericInterfaceType<String>(null));
+		assertThat(type.getType(), equalTo(MyGenericInterfaceType.class));
+		assertThat(type.resolve(), equalTo(MyGenericInterfaceType.class));
+	}
+
 	@Test
 	public void forField() throws Exception {
 		Field field = Fields.class.getField("charSequenceList");
@@ -1454,6 +1482,23 @@ public class ResolvableTypeTests {
 	public interface MyInterfaceType<T> {
 	}
 
+	public class MyGenericInterfaceType<T> implements MyInterfaceType<T>, ResolvableTypeProvider {
+
+		private final Class<T> type;
+
+		public MyGenericInterfaceType(Class<T> type) {
+			this.type = type;
+		}
+
+		@Override
+		public ResolvableType getResolvableType() {
+			if (this.type == null) {
+				return null;
+			}
+			return ResolvableType.forClassWithGenerics(getClass(), this.type);
+		}
+	}
+
 
 	public class MySimpleInterfaceType implements MyInterfaceType<String> {
 	}