code: public ToStringBuilder append(final String fieldName, final double value) {
          style.append(buffer, fieldName, value);
          return this;
      }
docs: <p>Append to the <code>toString</code> a <code>double</code>
  value.</p>
  
  @param fieldName  the field name
  @param value  the value to add to the <code>toString</code>
  @return this