nd4j-common/src/main/java/org/nd4j/util/StringUtils.java
public static String getFormattedTimeWithDiff(String formattedFinishTime,
                                                  long finishTime, long startTime){
        StringBuilder buf = new StringBuilder();
        if (0 != finishTime) {
            buf.append(formattedFinishTime);
            if (0 != startTime){
                buf.append(" (" + formatTimeDiff(finishTime , startTime) + ")");
            }
        }
        return buf.toString();
    }
public static String getFormattedTimeWithDiff(String formattedFinishTime,
                                                  long finishTime, long startTime){
        StringBuilder buf = new StringBuilder();
        if (0 != finishTime) {
            buf.append(formattedFinishTime);
            if (0 != startTime){
                buf.append(" (" + formatTimeDiff(finishTime , startTime) + ")");
            }
        }
        return buf.toString();
    }
Formats time in ms and appends difference (finishTime - startTime)
as returned by formatTimeDiff().
If finish time is 0, empty string is returned, if start time is 0
then difference is not appended to return value.
@param formattedFinishTime formattedFinishTime to use
@param finishTime finish time
@param startTime start time
@return formatted value.