code: private String fileToName(File policyFile) throws PolicyIndexException {
          try {
              if (!policyFile.getName().endsWith(".xml"))
                  throw new PolicyIndexException("Invalid policy file name.  Policy files must end in .xml - " + policyFile.getName());
  
              return PID.fromFilename(policyFile.getName().substring(0, policyFile.getName().lastIndexOf(".xml"))).toString();
          } catch (MalformedPIDException e) {
              throw new PolicyIndexException("Invalid policy file name.  Filename cannot be converted to a valid PID - " + policyFile.getName());
          }
  
      }
docs: Determine name of policy from file.  .xml prefix is removed, and name is converted to a PID.
  Policy names must be valid PIDs.
  @param policyFile
  @return
  @throws PolicyIndexException