java.util.function.Supplier<M> multimapSupplier) {
    return CollectCollectors.<T, K, V, M>toMultimap(keyFunction, valueFunction, multimapSupplier);
  }

  /**
   * Returns a {@code Collector} accumulating entries into a {@code Multimap} generated from the
   * specified supplier. Each input element is mapped to a key and a stream of values, each of which

    }
  }

  public void testForSupplier() {
    Supplier<Integer> supplier = new CountingSupplier();
    Function<@Nullable Object, Integer> function = Functions.forSupplier(supplier);

    assertEquals(1, (int) function.apply(null));
    assertEquals(2, (int) function.apply("foo"));

    new EqualsTester()
        .addEqualityGroup(function, Functions.forSupplier(supplier))

    }
  }

  public void testForSupplier() {
    Supplier<Integer> supplier = new CountingSupplier();
    Function<@Nullable Object, Integer> function = Functions.forSupplier(supplier);

    assertEquals(1, (int) function.apply(null));
    assertEquals(2, (int) function.apply("foo"));

    new EqualsTester()
        .addEqualityGroup(function, Functions.forSupplier(supplier))

        Supplier<Object> supplier = () -> null;

        monitorTarget.append(buf, "testKey", supplier);
        assertEquals("\"testKey\":null", buf.toString());
    }

    // Test append method with Integer value
    @Test
    public void test_append_integerValue() {
        StringBuilder buf = new StringBuilder();
        Supplier<Object> supplier = () -> Integer.valueOf(123);

import com.google.common.base.Supplier;
import java.util.concurrent.atomic.AtomicLong;

/**
 * Source of {@link LongAddable} objects that deals with GWT, Unsafe, and all that.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
final class LongAddables {
  private static final Supplier<LongAddable> SUPPLIER;

  static {
    Supplier<LongAddable> supplier;
    try {

package com.google.common.hash;

import com.google.common.base.Supplier;
import java.util.concurrent.atomic.AtomicLong;

/**
 * Source of {@link LongAddable} objects that deals with GWT, Unsafe, and all that.
 *
 * @author Louis Wasserman
 */
final class LongAddables {
  private static final Supplier<LongAddable> SUPPLIER;

  static {
    Supplier<LongAddable> supplier;
    try {

import com.google.common.base.Supplier;
import com.google.common.collect.ForwardingSet;
import java.util.Set;

/**
 * A subclass of `ForwardingSet` that throws `IllegalStateException` on invocation of any method
 * (except `hashCode` and `equals`) if the provided `Supplier` returns false.
 */
final class InvalidatableSet<E> extends ForwardingSet<E> {
  private final Supplier<Boolean> validator;
  private final Set<E> delegate;

     * @param supplier The function to execute and cache the result
     * @return The result from the supplier (either fresh or cached)
     * @throws RuntimeException Any exception thrown by the supplier will be cached and re-thrown on subsequent calls
     */
    <REQ extends Request<?>, REP extends Result<REQ>> REP request(REQ req, Function<REQ, REP> supplier);

    /**

    @Override
    public void debug(Throwable error) {
        logger.debug("", error);
    }

    @Override
    public void debug(Supplier<String> content) {
        if (isDebugEnabled()) {
            logger.debug(content.get());
        }
    }

    @Override
    public void debug(Supplier<String> content, Throwable error) {
        if (isDebugEnabled()) {
            logger.debug(content.get(), error);
        }
    }

        @SuppressWarnings("unchecked")
        Supplier<String> supplier = mock(Supplier.class);
        when(supplier.get()).thenThrow(new RuntimeException(new SmbUnsupportedOperationException("boom")));

        // Act & Assert: the exception is propagated and interaction recorded once
        RuntimeException thrown = assertThrows(RuntimeException.class, supplier::get);