/*****************************************************************************
* ------------------------------------------------------------------------- *
* 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, *
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package com.google.mu.util;
import static java.util.stream.Collectors.collectingAndThen;
import static java.util.stream.Collectors.toCollection;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.Objects;
import java.util.Set;
import java.util.stream.Collector;
import java.util.stream.Collectors;
final class InternalCollectors {
static <T> Collector<T, ?, Set<T>> toImmutableSet() {
return checkingNulls(
collectingAndThen(toCollection(LinkedHashSet::new), Collections::unmodifiableSet));
}
static <T, A, R> Collector<T, ?, R> checkingNulls(Collector<T, A, R> downstream) {
return Collectors.mapping(Objects::requireNonNull, downstream);
}
}
