code: @Override
  	@Nullable
  	public String getEncoding() {
  		return (this.dataSource instanceof EncodingAware) ? ((EncodingAware) this.dataSource).getEncoding() : null;
  	}
docs: Optimization to help Java Mail determine encoding for attachments.
  
  @return The encoding from the nested data source if it implements {@link EncodingAware} as well.
  @see <a href="https://github.com/bbottema/simple-java-mail/issues/131">Bug report #131</a>