Implement optional get<list>() methods in EvaluationContext as default methods

Author: sbrannen

spring-expression/src/main/java/org/springframework/expression/EvaluationContext.java

@@ -47,15 +47,18 @@ public interface EvaluationContext {
 
 	/**
 	 * Return the default root context object against which unqualified
-	 * properties/methods/etc should be resolved. This can be overridden
-	 * when evaluating an expression.
+	 * properties, methods, etc. should be resolved.
+	 * <p>This can be overridden when evaluating an expression.
 	 */
 	TypedValue getRootObject();
 
 	/**
 	 * Return a list of accessors that will be asked in turn to read/write a property.
+	 * <p>The default implementation returns an empty list.
 	 */
-	List<PropertyAccessor> getPropertyAccessors();
+	default List<PropertyAccessor> getPropertyAccessors() {
+		return Collections.emptyList();
+	}
 
 	/**
 	 * Return a list of index accessors that will be asked in turn to access or
@@ -69,13 +72,19 @@ default List<IndexAccessor> getIndexAccessors() {
 
 	/**
 	 * Return a list of resolvers that will be asked in turn to locate a constructor.
+	 * <p>The default implementation returns an empty list.
 	 */
-	List<ConstructorResolver> getConstructorResolvers();
+	default List<ConstructorResolver> getConstructorResolvers() {
+		return Collections.emptyList();
+	}
 
 	/**
 	 * Return a list of resolvers that will be asked in turn to locate a method.
+	 * <p>The default implementation returns an empty list.
 	 */
-	List<MethodResolver> getMethodResolvers();
+	default List<MethodResolver> getMethodResolvers() {
+		return Collections.emptyList();
+	}
 
 	/**
 	 * Return a bean resolver that can look up beans by name.

spring-expression/src/main/java/org/springframework/expression/spel/support/SimpleEvaluationContext.java

@@ -26,7 +26,6 @@
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.expression.BeanResolver;
-import org.springframework.expression.ConstructorResolver;
 import org.springframework.expression.EvaluationContext;
 import org.springframework.expression.MethodResolver;
 import org.springframework.expression.OperatorOverloader;
@@ -146,15 +145,6 @@ public List<PropertyAccessor> getPropertyAccessors() {
 		return this.propertyAccessors;
 	}
 
-	/**
-	 * Return an empty list, always, since this context does not support the
-	 * use of type references.
-	 */
-	@Override
-	public List<ConstructorResolver> getConstructorResolvers() {
-		return Collections.emptyList();
-	}
-
 	/**
 	 * Return the specified {@link MethodResolver} delegates, if any.
 	 * @see Builder#withMethodResolvers