code: public static boolean isGsi3Proxy(GSIConstants.CertificateType certType) {
          return certType == GSIConstants.CertificateType.GSI_3_IMPERSONATION_PROXY
                  || certType == GSIConstants.CertificateType.GSI_3_INDEPENDENT_PROXY
                  || certType == GSIConstants.CertificateType.GSI_3_RESTRICTED_PROXY
                  || certType == GSIConstants.CertificateType.GSI_3_LIMITED_PROXY;
      }
docs: Determines if a specified certificate type indicates a GSI-3 proxy
  certificate.
  
  @param certType the certificate type to check.
  @return true if certType is a GSI-3 proxy, false otherwise.