code: public static boolean isProxy(GSIConstants.CertificateType certType) {
          return isGsi2Proxy(certType) || isGsi3Proxy(certType) || isGsi4Proxy(certType);
      }
docs: Determines if a specified certificate type indicates a GSI-2, GSI-3 or
  GSI-4proxy certificate.
  
  @param certType the certificate type to check.
  @return true if certType is a GSI-2 or GSI-3 or GSI-4 proxy, false
  otherwise.