@Test
  public void testReadWriteStringToFile() throws IOException {
    File file = File.createTempFile("test", "1");
    file.deleteOnExit();
    Utils.writeStringToFile("Test", file.getPath());
    String outputString = Utils.readStringFromFile(file.getPath());
    Assert.assertEquals("Test", outputString);
  }
Return the internal byte array of the given {@link ByteBuffer}. It only works when the {@link ByteBuffer} is not
a direct {@link ByteBuffer}.
@param buffer The {@link ByteBuffer}.
@return The internal byte array.
@throws Exception Any unexpected error.
ambry-utils/src/test/java/com/github/ambry/utils/UtilsTest.java