code: public static int append (final int nPrevHashCode, @Nullable final Object x)
    {
      return append (nPrevHashCode, HashCodeImplementationRegistry.getHashCode (x));
    }
docs: Object hash code generation.
  
  @param nPrevHashCode
  The previous hash code used as the basis for calculation
  @param x
  Object to add. May be <code>null</code>.
  @return The updated hash code