code: @Nonnull
    public final UnifiedResponse setContentAndCharset (@Nonnull final String sContent, @Nonnull final Charset aCharset)
    {
      ValueEnforcer.notNull (sContent, "Content");
      setCharset (aCharset);
      setContent (sContent.getBytes (aCharset));
      return this;
    }
docs: Utility method to set content and charset at once.
  
  @param sContent
  The response content string. May not be <code>null</code>.
  @param aCharset
  The charset to use. May not be <code>null</code>.
  @return this