code: public static ContentType create(final String mimeType, final Charset charset) {
          if (mimeType == null) {
              throw new IllegalArgumentException("MIME type may not be null");
          }
          String type = mimeType.trim().toLowerCase(Locale.US);
          if (type.length() == 0) {
              throw new IllegalArgumentException("MIME type may not be empty");
          }
          if (!valid(type)) {
              throw new IllegalArgumentException("MIME type may not contain reserved characters");
          }
          return new ContentType(type, charset);
      }
docs: Creates a new instance of {@link ContentType}.
  
  @param mimeType MIME type. It may not be <code>null</code> or empty. It may not contain
  characters <">, <;>, <,> reserved by the HTTP specification.
  @param charset charset.
  @return content type