public static StringBuilder appendKeyValue(final StringBuilder sb, final String key,
    final Object value, final String separator, final String keyValueSeparator) {
    if (sb.length() > 0) {
      sb.append(keyValueSeparator);
    }
    return sb.append(key).append(separator).append(value);
  }
Append to a StringBuilder a key/value. Uses default separators.
@param sb                StringBuilder to use
@param key               Key to append.
@param value             Value to append.
@param separator         Value to use between key and value.
@param keyValueSeparator Value to use between key/value sets.
@return Passed <code>sb</code> populated with key/value.
hbase-common/src/main/java/org/apache/hadoop/hbase/util/Strings.java