private String buildMessage(String firstMessageLine, int exceptionLine, ParsingContext ctx) {
    if (ctx.getUnmatchedLog().length() == 0) {
      return firstMessageLine;
    }
    StringBuffer message = new StringBuffer();
    if (firstMessageLine != null) {
      message.append(firstMessageLine);
    }
    String[] additionalLines = ctx.getUnmatchedLog().toString().split("\n");
    int linesToProcess = (exceptionLine == -1 ? additionalLines.length : exceptionLine);

    for (int i = 0; i < linesToProcess; i++) {
      message.append(newLine);
      message.append(additionalLines[i]);
    }
    return message.toString();
  }
Combine all message lines occuring in the additionalLines list, adding a newline character between each line
<p>
the event will already have a message - combine this message with the message lines in the additionalLines list (all entries prior to the exceptionLine
index)

@param firstMessageLine
         primary message line
@param exceptionLine
         index of first exception line
@return message
olv-core/src/main/java/pl/otros/logview/parser/log4j/Log4jPatternMultilineLogParser.java