code: public static String getDateStampFromDumpFileDirectoryName(
  			DumpContentType dumpContentType, String directoryName) {
  		int prefixLength = dumpContentType.toString().length() + 1;
  		return directoryName.substring(prefixLength);
  	}
docs: Extracts the date stamp from a dumpfile directory name in the form that
  is created by {@link #getDumpFileDirectoryName(DumpContentType, String)}.
  It is not checked that the given directory name has the right format; if
  it has not, the result will not be a date stamp but some other string.
  
  @param dumpContentType
  @param directoryName
  @return the date stamp