Way to find full package name when it is not obvious

[jglick]

lib-support-log-formatter/src/main/java/io/jenkins/lib/support_log_formatter/SupportLogFormatter.java

Lines 105 to 140 in ec8e3de

	public String abbreviateClassName(String fqcn, int targetLength) {
	if (fqcn == null) {
	return "-";
	}
	int fqcnLength = fqcn.length();
	if (fqcnLength < targetLength) {
	return fqcn;
	}
	int[] indexes = new int[16];
	int[] lengths = new int[17];
	int count = 0;
	for (int i = fqcn.indexOf('.'); i != -1 && count < indexes.length; i = fqcn.indexOf('.', i + 1)) {
	indexes[count++] = i;
	}
	if (count == 0) {
	return fqcn;
	}
	StringBuilder buf = new StringBuilder(targetLength);
	int requiredSavings = fqcnLength - targetLength;
	for (int i = 0; i < count; i++) {
	int previous = i > 0 ? indexes[i - 1] : -1;
	int available = indexes[i] - previous - 1;
	int length = requiredSavings > 0 ? Math.min(available, 1) : available;
	requiredSavings -= available - length;
	lengths[i] = length + 1;
	}
	lengths[count] = fqcnLength - indexes[count - 1];
	for (int i = 0; i <= count; i++) {
	if (i == 0) {
	buf.append(fqcn, 0, lengths[i] - 1);
	} else {
	buf.append(fqcn, indexes[i - 1], indexes[i - 1] + lengths[i]);
	}
	}
	return buf.toString();
	}

is useful to reduce the size of log files and especially the horizontal width of log lines in the case of well-known packages. But on occasion a log message is printed from a class with a generic-sounding name and it is actually difficult to figure out which package this is coming from, even with GitHub code search. Ideas:

• Print the full package name the first time it is encountered in a given logger.
• Print the .protectionDomain.codeSource.location of a JAR (at least the filename, not necessary directory path; e.g. some-lib-1.23.jar) the first time it is encountered as the emitter of a log message. Trickier since https://docs.oracle.com/javase/10/docs/api/java/util/logging/LogRecord.html#getSourceClassName() does not record the Class so it would need to be searched for in the Thread.contextClassLoader.