code: public static boolean isGsi4Proxy(GSIConstants.CertificateType certType) {
          return certType == GSIConstants.CertificateType.GSI_4_IMPERSONATION_PROXY
                  || certType == GSIConstants.CertificateType.GSI_4_INDEPENDENT_PROXY
                  || certType == GSIConstants.CertificateType.GSI_4_RESTRICTED_PROXY
                  || certType == GSIConstants.CertificateType.GSI_4_LIMITED_PROXY;
      }
docs: Determines if a specified certificate type indicates a GSI-4 proxy
  certificate.
  
  @param certType the certificate type to check.
  @return true if certType is a GSI-4 proxy, false otherwise.