code: private void renameFile(File source, File target) {
          if (!source.exists()) {
              // don't do anything if the source file doesn't exist
              return;
          }
          if (target.exists()) {
              target.delete();
          }
          boolean rc = source.renameTo(target);
          if (!rc) {
              if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled()) {
                  Tr.debug(tc, getFileName() + ": Unable to rename " + source + " to " + target);
              }
          }
      }
docs: Rename the source file into the target file, deleting the target if
  necessary.
  
  @param source
  @param target