@Override
  public Object structuralValue(Void value) {
    return STRUCTURAL_VOID_VALUE;
  }
@Test
  public void testStructuralValueSharesSameObject() {
    assertEquals(TEST_CODER.structuralValue(null), TEST_CODER.structuralValue(null));
    // This is a minor performance optimization to not encode and compare empty byte
    // arrays.
    assertSame(TEST_CODER.structuralValue(null), TEST_CODER.structuralValue(null));
  }