Nullpointer Exception when injecting HttpRequest - jax-rs

Question

I have a Liberty JAX-RS 2.0 Application on Bluemix. My goal is to use the Bluemix Session Cache Service as a central session storage.
In my interface, I inject the HttpRequest object like this:
#Path("/resource")
public class MyResource {
#Post
public Response myOperation(..., #Context final HttpServletRequest httpRequest) {
...
}
}
This runs fine with just Liberty on its own (without Session Cache Binding on Bluemix). I do not even access the httpRequest in my test app, nor do I access httpRequest.getSession(). Once I bind the Session Cache service to the Liberty App and restage the app, I get the following upon calling the API:
java.lang.NullPointerException:
at com.ibm.ws.xs.sessionmanager.IBMHttpSessionListener.attributeAdded(IBMHttpSessionListener.java:265)
at com.ibm.ws.session.http.HttpSessionAttributeObserver.sessionAttributeSet(HttpSessionAttributeObserver.java:141)
at [internal classes]
at org.jboss.weld.context.AbstractConversationContext.copyConversationIdGeneratorAndConversationsToSession(AbstractConversationContext.java:188)
at org.jboss.weld.context.AbstractConversationContext.sessionCreated(AbstractConversationContext.java:196)
at org.jboss.weld.servlet.ConversationContextActivator.sessionCreated(ConversationContextActivator.java:190)
at [internal classes]
As requested, the server.xml - which is generated by Bluemix on deployment.
<server>
<featureManager>
<feature>jaxrs-2.0</feature>
<feature>jsonp-1.0</feature>
<feature>couchdb-1.0</feature>
<feature>ejb-3.2</feature>
<feature>cdi-1.2</feature>
<feature>icap:managementConnector-1.0</feature>
<feature>appstate-1.0</feature>
<feature>cloudAutowiring-1.0</feature>
<feature>eXtremeScale.webapp-1.1</feature>
</featureManager>
<application name='myapp' location='myapp.war' type='war' context-root='some-app'>
<classloader commonLibraryRef='cloudantNoSQLDB-library'/>
</application>
<cdi12 enableImplicitBeanArchives='false'/>
<httpEndpoint id='defaultHttpEndpoint' host='*' httpPort='${port}'/>
<webContainer trustHostHeaderPort='true' extractHostHeaderPort='true'/>
<include location='runtime-vars.xml'/>
<logging logDirectory='${application.log.dir}' consoleLogLevel='INFO'/>
<httpDispatcher enableWelcomePage='false'/>
<applicationMonitor dropinsEnabled='false' updateTrigger='mbean'/>
<config updateTrigger='mbean'/>
<appstate appName='myapp' markerPath='${home}/../.liberty.state'/>
<couchdb id='cloudantNoSQLDB-ith-auth-db' jndiName='couchdb/ith-auth-db' libraryRef='cloudantNoSQLDB-library' username='${cloud.services.ith-auth-db.connection.username}' password='${cloud.services.ith-auth-db.connection.password}' url='${cloud.services.ith-auth-db.connection.url}' enableSSL='true' host='${cloud.services.ith-auth-db.connection.host}' port='${cloud.services.ith-auth-db.connection.port}'/>
<library id='cloudantNoSQLDB-library'>
<fileset id='cloudantNoSQLDB-fileset' dir='${server.config.dir}/lib' includes='commons-codec-1.6.jar commons-io-2.0.1.jar commons-logging-1.1.3.jar httpclient-4.3.6.jar httpclient-cache-4.3.6.jar httpcore-4.3.3.jar jackson-annotations-2.2.2.jar jackson-core-2.2.2.jar jackson-databind-2.2.2.jar jcl-over-slf4j-1.6.6.jar org.ektorp-1.4.2.jar slf4j-api-1.6.6.jar slf4j-jdk14-1.6.6.jar'/>
</library>
<xsWebApp id='session-cache' objectGridName='${cloud.services.session-cache.connection.gridName}' catalogHostPort='${cloud.services.session-cache.connection.catalogEndPoint}' credentialGeneratorClass='com.ibm.websphere.objectgrid.security.plugins.builtins.UserPasswordCredentialGenerator' credentialGeneratorProps='${cloud.services.session-cache.connection.username} ${cloud.services.session-cache.connection.password}' objectGridType='REMOTE' securityEnabled='true'/>
So I guess something goes wrong with injecting the HttpRequest... how can I solve this?