Monitoring of direct-memory could be made resilient

[sabbyanandan]

As an SCDF user, while using the latest JBP (on PWS), I observe the following error when deploying the application that instantiates CFJC.

   2017-11-20T12:06:20.84-0800 [APP/PROC/WEB/0] OUT 2017-11-20 20:06:20.840  INFO 12 --- [           main] o.s.jdbc.datasource.init.ScriptUtils     : Executed SQL script from class path resource [org/springframework/cloud/task/schema-mysql.sql] in 25 ms.
   2017-11-20T12:06:21.16-0800 [APP/PROC/WEB/0] OUT 2017-11-20 20:06:21.166  INFO 12 --- [           main] ContainerTrustManagerFactory$PKIXFactory : Adding System Trust Manager
   2017-11-20T12:06:21.16-0800 [APP/PROC/WEB/0] OUT 2017-11-20 20:06:21.167  INFO 12 --- [           main] ContainerTrustManagerFactory$PKIXFactory : Adding TrustManager for /etc/ssl/certs/ca-certificates.crt
   2017-11-20T12:06:21.17-0800 [APP/PROC/WEB/0] OUT 2017-11-20 20:06:21.173  INFO 12 --- [ertificates.crt] org.cloudfoundry.security.FileWatcher    : Start watching /etc/ssl/certs/ca-certificates.crt
   2017-11-20T12:06:21.20-0800 [APP/PROC/WEB/0] OUT 2017-11-20 20:06:21.203  INFO 12 --- [           main] c.s.FileWatchingX509ExtendedTrustManager : Initialized TrustManager for /etc/ssl/certs/ca-certificates.crt
   2017-11-20T12:06:21.22-0800 [APP/PROC/WEB/0] OUT 2017-11-20 20:06:21.222 ERROR 12 --- [           main] cloudfoundry-client                      : Unable to register ByteBufAllocator MBean
   2017-11-20T12:06:21.22-0800 [APP/PROC/WEB/0] OUT javax.management.InstanceAlreadyExistsException: org.cloudfoundry.reactor:type=ByteBufAllocator
   2017-11-20T12:06:21.22-0800 [APP/PROC/WEB/0] OUT 	at com.sun.jmx.mbeanserver.Repository.addMBean(Repository.java:437) ~[na:1.8.0_141]

@nebhale's observation here: spring-attic/spring-cloud-dataflow-server-cloudfoundry#367