code: public static void unescapeJson(final String text, final Writer writer)
              throws IOException {
  
          if (writer == null) {
              throw new IllegalArgumentException("Argument 'writer' cannot be null");
          }
          if (text == null) {
              return;
          }
          if (text.indexOf('\\') < 0) {
              // Fail fast, avoid more complex (and less JIT-table) method to execute if not needed
              writer.write(text);
              return;
          }
  
          JsonEscapeUtil.unescape(new InternalStringReader(text), writer);
  
      }
docs: <p>
  Perform a JSON <strong>unescape</strong> operation on a <tt>String</tt> input, writing
  results to a <tt>Writer</tt>.
  </p>
  <p>
  No additional configuration arguments are required. Unescape operations
  will always perform <em>complete</em> JSON unescape of SECs and u-based escapes.
  </p>
  <p>
  This method is <strong>thread-safe</strong>.
  </p>
  
  @param text the <tt>String</tt> to be unescaped.
  @param writer the <tt>java.io.Writer</tt> to which the unescaped result will be written. Nothing will
  be written at all to this writer if input is <tt>null</tt>.
  @throws IOException if an input/output exception occurs
  
  @since 1.1.2