Description of problem:
=======================
 - JDG client unable to resolve the system property which is added in external-host jdg6.6.1 server

Version-Release number of selected component (if applicable):
==============================================================
 - JBoss DG 6.6.x


Steps to Reproduce:
===================
1) Add below configuration in jdg 6.6.1 clustered.xml file:
-------
    <system-properties>
        <property name="infinispan.external_addr" value="10.65.193.123"/>
    </system-properties>
             :
        <subsystem xmlns="urn:infinispan:server:endpoint:6.1">
        
            <hotrod-connector cache-container="clustered" socket-binding="hotrod">
                <topology-state-transfer  external-host="${infinispan.external_addr}"  lazy-retrieval="false" lock-timeout="1000" replication-timeout="5000"/>
            </hotrod-connector>
               ..........
        </subsystem>
-------

2) Client unable to resolve the value assigned for the `infinispan.external_addr`:

Here is the TRACE level logging:
------
2017-02-16 14:31:32 TRACE AbstractTransport:34 - Read string is: ${infinispan.external_addr}
2017-02-16 14:31:32 TRACE AbstractTransport:34 - Read string is: ${infinispan.external_addr}
2017-02-16 14:31:32 TRACE TcpTransport:211 - Offset: 0, len=2, size=2
2017-02-16 14:31:32 TRACE TcpTransport:211 - Offset: 0, len=2, size=2
2017-02-16 14:31:32 TRACE TcpTransport:231 - Successfully read array with size: 2
2017-02-16 14:31:32 TRACE TcpTransport:231 - Successfully read array with size: 2
2017-02-16 14:31:32 TRACE TcpTransport:180 - Read byte 3 from socket input in Socket[addr=localhost/127.0.0.1,port=11222,localport=55162]
   ............
2017-02-16 14:31:32 INFO  Codec21:413 - ISPN004006: localhost/127.0.0.1:11222 sent new topology view (id=0, age=0) containing 1 addresses: [${infinispan.external_addr}:11222]
2017-02-16 14:31:32 INFO  Codec21:413 - ISPN004006: localhost/127.0.0.1:11222 sent new topology view (id=0, age=0) containing 1 addresses: [${infinispan.external_addr}:11222]
2017-02-16 14:31:32 TRACE TcpTransportFactory:371 - Current list: [localhost/127.0.0.1:11222]
2017-02-16 14:31:32 TRACE TcpTransportFactory:371 - Current list: [localhost/127.0.0.1:11222]
2017-02-16 14:31:32 TRACE TcpTransportFactory:372 - New list: [${infinispan.external_addr}:11222]
2017-02-16 14:31:32 TRACE TcpTransportFactory:372 - New list: [${infinispan.external_addr}:11222]
2017-02-16 14:31:32 TRACE TcpTransportFactory:373 - Added servers: [${infinispan.external_addr}:11222]
2017-02-16 14:31:32 TRACE TcpTransportFactory:373 - Added servers: [${infinispan.external_addr}:11222]
2017-02-16 14:31:32 TRACE TcpTransportFactory:374 - Removed servers: [localhost/127.0.0.1:11222]
2017-02-16 14:31:32 TRACE TcpTransportFactory:374 - Removed servers: [localhost/127.0.0.1:11222]
2017-02-16 14:31:32 INFO  TcpTransportFactory:384 - ISPN004014: New server added(${infinispan.external_addr}:11222), adding to the pool.
2017-02-16 14:31:32 INFO  TcpTransportFactory:384 - ISPN004014: New server added(${infinispan.external_addr}:11222), adding to the pool.
2017-02-16 14:31:32 TRACE TcpTransport:75 - Could not connect to server: ${infinispan.external_addr}:11222
java.net.UnknownHostException
------