Find CORS config by HandlerMethod

Before this change AbstractHandlerMethodMapping used a map from Method
to CorsConfiguration. That works for regular @RequestMapping methods.
However frameworks like Spring Boot and Spring Integration may
programmatically register the same Method under multiple mappings,
i.e. adapter/gateway type classes.

This change ensures that CorsConfiguraiton is indexed by HandlerMethod
so that we can store CorsConfiguration for different handler instances
even when the method is the same.

In order for to make this work, HandlerMethod now provides an
additional field called resolvedFromHandlerMethod that returns the
original HandlerMethod (with the String bean name). This makes it
possible to  perform reliable lookups.

Issue: SPR-11541

spring-web/src/main/java/org/springframework/web/method/HandlerMethod.java

@@ -60,6 +60,8 @@ public class HandlerMethod {
 
 	private final MethodParameter[] parameters;
 
+	private final HandlerMethod resolvedFromHandlerMethod;
+
 
 	/**
 	 * Create an instance from a bean instance and a method.
@@ -73,6 +75,7 @@ public class HandlerMethod {
 		this.method = method;
 		this.bridgedMethod = BridgeMethodResolver.findBridgedMethod(method);
 		this.parameters = initMethodParameters();
+		this.resolvedFromHandlerMethod = null;
 	}
 
 	/**
@@ -88,6 +91,7 @@ public class HandlerMethod {
 		this.method = bean.getClass().getMethod(methodName, parameterTypes);
 		this.bridgedMethod = BridgeMethodResolver.findBridgedMethod(this.method);
 		this.parameters = initMethodParameters();
+		this.resolvedFromHandlerMethod = null;
 	}
 
 	/**
@@ -105,6 +109,7 @@ public class HandlerMethod {
 		this.method = method;
 		this.bridgedMethod = BridgeMethodResolver.findBridgedMethod(method);
 		this.parameters = initMethodParameters();
+		this.resolvedFromHandlerMethod = null;
 	}
 
 	/**
@@ -118,6 +123,7 @@ public class HandlerMethod {
 		this.method = handlerMethod.method;
 		this.bridgedMethod = handlerMethod.bridgedMethod;
 		this.parameters = handlerMethod.parameters;
+		this.resolvedFromHandlerMethod = handlerMethod.resolvedFromHandlerMethod;
 	}
 
 	/**
@@ -132,6 +138,7 @@ public class HandlerMethod {
 		this.method = handlerMethod.method;
 		this.bridgedMethod = handlerMethod.bridgedMethod;
 		this.parameters = handlerMethod.parameters;
+		this.resolvedFromHandlerMethod = handlerMethod;
 	}
 
 
@@ -182,6 +189,14 @@ public class HandlerMethod {
 		return this.parameters;
 	}
 
+	/**
+	 * Return the HandlerMethod from which this HandlerMethod instance was
+	 * resolved via {@link #createWithResolvedBean()}.
+	 */
+	public HandlerMethod getResolvedFromHandlerMethod() {
+		return this.resolvedFromHandlerMethod;
+	}
+
 	/**
 	 * Return the HandlerMethod return type.
 	 */