public static boolean equal(File file1, File file2) throws IOException {
    checkNotNull(file1);
    checkNotNull(file2);
    if (file1 == file2 || file1.equals(file2)) {
      return true;
    }

    /*
     * Some operating systems may return zero as the length for files denoting system-dependent
     * entities such as devices or pipes, in which case we must fall back on comparing the bytes
     * directly.
     */

import static java.nio.file.attribute.PosixFilePermission.OWNER_EXECUTE;
import static java.nio.file.attribute.PosixFilePermission.OWNER_READ;
import static java.nio.file.attribute.PosixFilePermission.OWNER_WRITE;
import static org.junit.Assert.assertThrows;

import java.io.File;
import java.io.IOException;
import java.nio.file.attribute.PosixFileAttributeView;
import java.nio.file.attribute.PosixFileAttributes;

    util.concurrent tests under Guava.

    The problem is that GWT responds poorly to two .gwt.xml files in the same
    Java package; see https://goo.gl/pRV3Yn for details.

    The summary is that it ignores one file in favor of the other.
    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

    util.concurrent tests under Guava.

    The problem is that GWT responds poorly to two .gwt.xml files in the same
    Java package; see https://goo.gl/pRV3Yn for details.

    The summary is that it ignores one file in favor of the other.
    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

    util.concurrent tests under Guava.

    The problem is that GWT responds poorly to two .gwt.xml files in the same
    Java package; see https://goo.gl/pRV3Yn for details.

    The summary is that it ignores one file in favor of the other.
    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

     has good test coverage, so look at some existing tests if you're unsure
     how to go about it.
  2. All contributions must be licensed Apache 2.0 and all files must have a
     copy of the boilerplate license comment (can be copied from an existing
     file).
  3. Files should be formatted according to Google's [Java style guide][].
  4. Please squash all commits for a change into a single commit (this can be

 * identical to the original.
 *
 * @author Chris Povirk
 */
/*
 * The whole thing is really @GwtIncompatible, but GwtJUnitConvertedTestModule doesn't have a
 * parameter for non-GWT, non-test files, and it didn't seem worth adding one for this unusual case.
 */
@GwtCompatible(emulated = true)
final class LenientSerializableTester {
  /*

import com.google.common.annotations.J2ktIncompatible;
import com.google.common.base.Preconditions;
import java.io.File;
import java.io.FilenameFilter;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;

/**
 * File name filter that only accepts files matching a regular expression. This class is thread-safe
 * and immutable.
 *
 * @author Apple Chow
 * @since 1.0
 */

 *       a more precisely named annotation?
 *   <li>While a dependency on Android ought to be easy if it's for annotations only, it will
 *       probably require adding the dep to various ACLs, license files, and Proguard
 *       configurations, and there's always the potential that something will go wrong. It
 *       <i>probably</i> won't, since the deps are needed only in tests (and maybe someday in
 *       testlib), but why bother?

      assertTrue(file.exists());
      assertThat(file.getName()).contains("FileBackedOutputStream");
      if (!isAndroid() && !isWindows()) {
        PosixFileAttributes attributes =
            java.nio.file.Files.getFileAttributeView(file.toPath(), PosixFileAttributeView.class)
                .readAttributes();
        assertThat(attributes.permissions()).containsExactly(OWNER_READ, OWNER_WRITE);
      }
    }
    out.close();