code: protected BodyPart handleTextPart(MimePart textPart, String contentType) throws IOException, MessagingException {
  
          String content;
          if (textPart.getContent() instanceof String) {
              content = (String) textPart.getContent();
          } else if (textPart.getContent() instanceof InputStream) {
              content = FileUtils.readToString((InputStream) textPart.getContent(), Charset.forName(parseCharsetFromContentType(contentType)));
          } else {
              throw new CitrusRuntimeException("Cannot handle text content of type: " + textPart.getContent().getClass().toString());
          }
  
          return new BodyPart(stripMailBodyEnding(content), contentType);
      }
docs: Construct simple binary body part with base64 data.
  @param textPart
  @param contentType
  @return
  @throws IOException