Not being able to disable Security Token Service in Resident Identity Provider

[mathuriga]

Product version: WSO2IS 5.3.0 onwards

Steps to reproduce:

1. Configure STS under the Resident Identity Provider section of the Identity Server Management Console. (Please refer Configure STS in WSO2 IS documentation to configure STS.
2. Go to configured Security Token Service.
3. Disable the configured Security Token Service by Selecting 'No' in the Enable Security?
4. You will notice the error message "Could not disable security. The system failed to authorize." and below exception in the back end.

[2018-09-26 10:49:14,171] ERROR {java.lang.Class} - System failed to authorize.null java.lang.NullPointerException at org.wso2.carbon.server.admin.module.handler.AuthorizationHandler.doAuthorization(AuthorizationHandler.java:118) at org.wso2.carbon.server.admin.module.handler.AuthorizationHandler.invoke(AuthorizationHandler.java:87) at org.apache.axis2.engine.Phase.invokeHandler(Phase.java:340) at org.apache.axis2.engine.Phase.invoke(Phase.java:313) at org.apache.axis2.engine.AxisEngine.invoke(AxisEngine.java:261) at org.apache.axis2.engine.AxisEngine.receive(AxisEngine.java:167) at org.apache.axis2.transport.local.LocalTransportReceiver.processMessage(LocalTransportReceiver.java:169) at org.apache.axis2.transport.local.LocalTransportReceiver.processMessage(LocalTransportReceiver.java:82) at org.wso2.carbon.core.transports.local.CarbonLocalTransportSender.finalizeSendWithToAddress(CarbonLocalTransportSender.java:45) at org.apache.axis2.transport.local.LocalTransportSender.invoke(LocalTransportSender.java:77) at org.apache.axis2.engine.AxisEngine.send(AxisEngine.java:442) at org.apache.axis2.description.OutInAxisOperationClient.send(OutInAxisOperation.java:430) at org.apache.axis2.description.OutInAxisOperationClient.executeImpl(OutInAxisOperation.java:225) at org.apache.axis2.client.OperationClient.execute(OperationClient.java:149) at org.wso2.carbon.security.mgt.stub.config.SecurityAdminServiceStub.disableSecurityOnService(SecurityAdminServiceStub.java:1105) at org.wso2.carbon.security.ui.client.SecurityAdminClient.disableSecurityOnService(SecurityAdminClient.java:78) at org.apache.jsp.securityconfig.remove_002dsecurity_jsp._jspService(remove_002dsecurity_jsp.java:125) at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) at javax.servlet.http.HttpServlet.service(HttpServlet.java:731) at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:439) at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395) at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339) at javax.servlet.http.HttpServlet.service(HttpServlet.java:731) at org.wso2.carbon.ui.JspServlet.service(JspServlet.java:155) at org.wso2.carbon.ui.TilesJspServlet.service(TilesJspServlet.java:80) at javax.servlet.http.HttpServlet.service(HttpServlet.java:731) at org.eclipse.equinox.http.helper.ContextPathServletAdaptor.service(ContextPathServletAdaptor.java:37) at org.eclipse.equinox.http.servlet.internal.ServletRegistration.service(ServletRegistration.java:61) at org.eclipse.equinox.http.servlet.internal.ProxyServlet.processAlias(ProxyServlet.java:128) at org.eclipse.equinox.http.servlet.internal.ProxyServlet.service(ProxyServlet.java:68) at javax.servlet.http.HttpServlet.service(HttpServlet.java:731) at org.wso2.carbon.tomcat.ext.servlet.DelegationServlet.service(DelegationServlet.java:68) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:747) at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:603) at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:542) at org.eclipse.equinox.http.servlet.internal.RequestDispatcherAdaptor.include(RequestDispatcherAdaptor.java:37) at org.eclipse.equinox.http.helper.ContextPathServletAdaptor$RequestDispatcherAdaptor.include(ContextPathServletAdaptor.java:369)