Picketlink/EAP 6.4.17 is passing the values as a system property but after an update to 6.4.18,  variables aren't resolved anymore at picketlink startup.
{code}
<PicketLink xmlns="urn:picketlink:identity-federation:config:2.1">
        <PicketLinkSP xmlns="urn:picketlink:identity-federation:config:2.1"
                BindingType="POST"
                LogOutPage="/myLogoutPage"
                IDPUsesPostBinding="true"
                SupportsSignatures="true">

                <IdentityURL>${plink.IDPurl}</IdentityURL>
                <ServiceURL>${plink.SPurl}</ServiceURL>
...
{code}

in standalone.xml we defined the system properties:
{code}
<system-properties>
...
      <property name="plink.IDPurl" value="https://www.myidp.com"/>
      <property name="plink.SPurl" value="https://mysp.com/"/>
...
{code}

Error Snippet:
{code}
2017-10-10 15:34:12,930 ERROR [org.picketlink.common] (ServerService Thread Pool -- 64) Exception creating TrustKeyManager:: java.net.MalformedURLException: no protocol: ${plink.IDPurl}
{code}

The fix for BZ1414138 is the cause of the issue.