code: public static String removeEmptyLine(String str) {
          assertStringNotNull(str);
          final StringBuilder sb = new StringBuilder();
          final List<String> lineList = splitList(str, "\n");
          for (String line : lineList) {
              if (is_Null_or_TrimmedEmpty(line)) {
                  continue; // skip
              }
              sb.append(removeCR(line)).append("\n");
          }
          final String filtered = sb.toString();
          return filtered.substring(0, filtered.length() - "\n".length());
      }
docs: Remove empty lines. <br>
  And CR is removed.
  @param str The target string. (NotNull)
  @return The filtered string. (NotNull)