/*
* Copyright 2015 Google Inc. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.errorprone.bugpatterns;
import static com.google.errorprone.BugPattern.Category.GUAVA;
import static com.google.errorprone.BugPattern.SeverityLevel.ERROR;
import com.google.common.util.concurrent.AsyncCallable;
import com.google.errorprone.BugPattern;
/** Checks that {@link AsyncCallable} implementations do not directly {@code return null}. */
@BugPattern(
name = "AsyncCallableReturnsNull",
summary = "AsyncCallable should not return a null Future, only a Future whose result is null.",
explanation =
"Methods like Futures.whenAllComplete(...).callAsync(...) will throw a "
+ "NullPointerException if the provided AsyncCallable returns a null Future. To produce "
+ "a Future with an output of null, instead return immediateFuture(null).",
category = GUAVA,
severity = ERROR
)
public final class AsyncCallableReturnsNull extends AbstractAsyncTypeReturnsNull {
public AsyncCallableReturnsNull() {
super(AsyncCallable.class);
}
}