Introduced ACL.lambda convenience method (#3260)

* Introduced ACL.lambda convenience method.

* Javadoc

core/src/main/java/hudson/model/User.java

@@ -977,14 +977,10 @@ public class User extends AbstractModelObject implements AccessControlled, Descr
     }
 
     public ACL getACL() {
-        final ACL base = Jenkins.getInstance().getAuthorizationStrategy().getACL(this);
+        ACL base = Jenkins.getInstance().getAuthorizationStrategy().getACL(this);
         // always allow a non-anonymous user full control of himself.
-        return new ACL() {
-            public boolean hasPermission(Authentication a, Permission permission) {
-                return (idStrategy().equals(a.getName(), id) && !(a instanceof AnonymousAuthenticationToken))
-                        || base.hasPermission(a, permission);
-            }
-        };
+        return ACL.lambda((a, permission) -> (idStrategy().equals(a.getName(), id) && !(a instanceof AnonymousAuthenticationToken))
+                        || base.hasPermission(a, permission));
     }
 
     /**

core/src/main/java/hudson/security/ACL.java

@@ -34,6 +34,7 @@ import hudson.model.Item;
 import hudson.remoting.Callable;
 import hudson.model.ItemGroup;
 import hudson.model.TopLevelItemDescriptor;
+import java.util.function.BiFunction;
 import jenkins.security.NonSerializableSecurityContext;
 import jenkins.model.Jenkins;
 import jenkins.security.NotReallyRoleSensitiveCallable;
@@ -95,6 +96,21 @@ public abstract class ACL {
      */
     public abstract boolean hasPermission(@Nonnull Authentication a, @Nonnull Permission permission);
 
+    /**
+     * Creates a simple {@link ACL} implementation based on a “single-abstract-method” easily implemented via lambda syntax.
+     * @param impl the implementation of {@link ACL#hasPermission(Authentication, Permission)}
+     * @return an adapter to that lambda
+     * @since FIXME
+     */
+    public static ACL lambda(final BiFunction<Authentication, Permission, Boolean> impl) {
+        return new ACL() {
+            @Override
+            public boolean hasPermission(Authentication a, Permission permission) {
+                return impl.apply(a, permission);
+            }
+        };
+    }
+
     /**
      * Checks if the current security principal has the permission to create top level items within the specified
      * item group.

core/src/main/java/hudson/security/AuthorizationStrategy.java

@@ -95,9 +95,7 @@ public abstract class AuthorizationStrategy extends AbstractDescribableImpl<Auth
      * @since 1.220
      */
     public @Nonnull ACL getACL(final @Nonnull View item) {
-        return new ACL() {
-            @Override
-            public boolean hasPermission(Authentication a, Permission permission) {
+        return ACL.lambda((a, permission) -> {
                 ACL base = item.getOwner().getACL();
 
                 boolean hasPermission = base.hasPermission(a, permission);
@@ -106,8 +104,7 @@ public abstract class AuthorizationStrategy extends AbstractDescribableImpl<Auth
                 }
 
                 return hasPermission;
-            }
-        };
+        });
     }
     
     /**
@@ -225,12 +222,7 @@ public abstract class AuthorizationStrategy extends AbstractDescribableImpl<Auth
             return Collections.emptySet();
         }
 
-        private static final ACL UNSECURED_ACL = new ACL() {
-            @Override
-            public boolean hasPermission(Authentication a, Permission permission) {
-                return true;
-            }
-        };
+        private static final ACL UNSECURED_ACL = ACL.lambda((a, p) -> true);
 
         @Extension @Symbol("unsecured")
         public static final class DescriptorImpl extends Descriptor<AuthorizationStrategy> {

core/src/test/java/hudson/model/TaskActionTest.java

@@ -45,11 +45,7 @@ public class TaskActionTest {
         }
 
         protected ACL getACL() {
-            return new ACL() {
-                public boolean hasPermission(Authentication a, Permission permission) {
-                     return true;
-                }
-            };
+            return ACL.lambda((a, p) -> true);
         }
     }