managed both idle and active connections for HTTP/2, but only idle
    connections for HTTP/1.x. With this update the connection pool manages both
    idle and active connections for everything. OkHttp now detects and warns on
    connections that were allocated but never released, and will enforce HTTP/2
    stream limits. This update also fixes `Call.cancel()` to not do I/O on the

 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *

// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//

// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//

    if (returnValue == null) {
      Assert.assertTrue(
          factory + " returns null but it's not annotated with @Nullable", isNullable(factory));
    }
    return returnValue;
  }

  /**
   * Thrown if the test tries to invoke a constructor or static factory method but failed because
   * the dummy value of a constructor or method parameter is unknown.
   */
  @VisibleForTesting

/**
 * A generic JUnit test which tests multiset-specific serialization. Can't be invoked directly;
 * please see {@link MultisetTestSuiteBuilder}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible // but no-op
@Ignore("test runners must not instantiate and run this directly, only via suites we build")
// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.

    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
    for prod and one for tests. However, unlike our other packages, as of this
    writing it has test supersource but no prod supersource.

    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
    tests, either. This causes it to fail to find AtomicLongMapTest.

    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
    for prod and one for tests. However, unlike our other packages, as of this
    writing it has test supersource but no prod supersource.

    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
    tests, either. This causes it to fail to find AtomicLongMapTest.

/**
 * A generic JUnit test which tests multiset-specific serialization. Can't be invoked directly;
 * please see {@link MultisetTestSuiteBuilder}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible // but no-op
@Ignore("test runners must not instantiate and run this directly, only via suites we build")
// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.

 */

package com.google.common.base;

import com.google.common.annotations.GwtCompatible;

/**
 * A time source; returns a time value representing the number of nanoseconds elapsed since some
 * fixed but arbitrary point in time. Note that most users should use {@link Stopwatch} instead of
 * interacting with this class directly.
 *
 * <p><b>Warning:</b> this interface can only be used to measure elapsed time, not wall time.
 *