private static void findPkgsInJar(String jarFilename, String pkgName,
			HashSet<String> pkgNames) {

		try (JarFile jarFile = new JarFile(jarFilename);) {

			String pkgPath = pkgName != null ? pkgName.replace('.', JAR_FILE_SEPARATOR) : "";
			if (pkgPath.length() > 0) {
				pkgPath += JAR_FILE_SEPARATOR;
			}
			int lastSepIx = pkgPath.length() - 1;

			String pkgPrefix = pkgName;
			if (pkgName != null && pkgName.length() > 0) {
				pkgPrefix += '.';
			}

			Enumeration<JarEntry> entries = jarFile.entries();
			while (entries.hasMoreElements()) {
				JarEntry entry = entries.nextElement();
				String name = entry.getName();
				if (!name.endsWith(".class")) {
					continue; // file is not a class file
				}
				if (lastSepIx != -1) {
					if (name.indexOf(pkgPath) != 0) {
						continue; // file not contained within specified package
					}
					name = name.substring(lastSepIx + 1);
				}
				int ix = name.indexOf(JAR_FILE_SEPARATOR);
				if (ix > 0) {
					name = pkgPrefix + name.substring(0, ix);
					if (!pkgNames.contains(name)) {
						pkgNames.add(name);
					}
				}
			}
		}
		catch (IOException e) {
			//System.out.println("searchJarFile: " + e);
			return;
		}
	}
Find and add to pkgNames, all packages contained within the specified package
which contain an AllTests class.
@param jarFilename jar filename
@param pkgName name of package
@param searchClass base or interface class to search for.
@param classNames set of unique class names
Ghidra/Framework/Generic/src/main/java/ghidra/util/TestSuiteUtilities.java