logback-android/src/main/java/ch/qos/logback/classic/Logger.java
Logger createChildByLastNamePart(final String lastPart) {
    int i_index = LoggerNameUtil.getFirstSeparatorIndexOf(lastPart);
    if (i_index != -1) {
      throw new IllegalArgumentException("Child name [" + lastPart
          + " passed as parameter, may not include [" + CoreConstants.DOT + "]");
    }

    if (childrenList == null) {
      childrenList = new CopyOnWriteArrayList<Logger>();
    }
    Logger childLogger;
    if (this.isRootLogger()) {
      childLogger = new Logger(lastPart, this, this.loggerContext);
    } else {
      childLogger = new Logger(name + CoreConstants.DOT + lastPart, this,
          this.loggerContext);
    }
    childrenList.add(childLogger);
    childLogger.effectiveLevelInt = this.effectiveLevelInt;
    return childLogger;
  }
Logger createChildByLastNamePart(final String lastPart) {
    int i_index = LoggerNameUtil.getFirstSeparatorIndexOf(lastPart);
    if (i_index != -1) {
      throw new IllegalArgumentException("Child name [" + lastPart
          + " passed as parameter, may not include [" + CoreConstants.DOT + "]");
    }

    if (childrenList == null) {
      childrenList = new CopyOnWriteArrayList<Logger>();
    }
    Logger childLogger;
    if (this.isRootLogger()) {
      childLogger = new Logger(lastPart, this, this.loggerContext);
    } else {
      childLogger = new Logger(name + CoreConstants.DOT + lastPart, this,
          this.loggerContext);
    }
    childrenList.add(childLogger);
    childLogger.effectiveLevelInt = this.effectiveLevelInt;
    return childLogger;
  }
Create a child of this logger by suffix, that is, the part of the name
extending this logger. For example, if this logger is named "x.y" and the
lastPart is "z", then the created child logger will be named "x.y.z".

<p>
IMPORTANT: Calls to this method must be within a synchronized block on this
logger.

@param lastPart
the suffix (i.e. last part) of the child logger name. This
parameter may not include dots, i.e. the logger separator
character.
@return