ViewRegistry getViewRegistry() {
    return ViewRegistry.getInstance();
  }
Get the parameter value from the given servlet filter configuration.

@param filterConfig  the servlet configuration
@param parameterName the parameter name
@param defaultValue  the default value
@return the parameter value or the default value if not set
ambari-server/src/main/java/org/apache/ambari/server/security/authorization/AmbariAuthorizationFilter.java