Host bundle's Bundle-Blueprint manifest header should be able to reference a blueprint XML document from it’s fragment bundle

Issue

The OSGi Service Platform Enterprise Specification part 121.3.4 says:

A Bundle-Blueprint manifest header specified in a fragment is ignored by the Blueprint Container. However, XML documents referenced by a bundle’s Bundle-Blueprint manifest header, or its default, may be contained in attached fragments, as defined by the findEntries method.
So my understanding is that in host bundle, it’s Bundle-Blueprint manifest header can reference a blueprint XML document from it’s fragment bundle.

However, I tested it out but it does not seem that Aries is specification compliant on this.

Say, I have a fragment bundle and I have a blueprint xml file called "custom.xml" under it’s "src/main/resources/OSGI-INF/blueprint” folder. And then in a host bundle, I tried to reference this blueprint XML from it’s Bundle-Blueprint manifest header:
Bundle-Blueprint: OSGI-INF/blueprint/custom.xml

But wen I tried to deploy them, Aries Blueprint just threw the following exception back to me:

19:09:58,740 | ERROR | rint Extender: 2 | BlueprintContainerImpl           | 21 - org.apache.aries.blueprint.core - 1.4.2 | Unable to start blueprint container for bundle jda.fuse.examples.blueprint-fragment-master
java.io.FileNotFoundException: Unable to find configuration file for OSGI-INF/blueprint/custom.xml
    at org.apache.aries.blueprint.container.BlueprintContainerImpl.getResources(BlueprintContainerImpl.java:420)[21:org.apache.aries.blueprint.core:1.4.2]
    at org.apache.aries.blueprint.container.BlueprintContainerImpl.doRun(BlueprintContainerImpl.java:298)[21:org.apache.aries.blueprint.core:1.4.2]
    at org.apache.aries.blueprint.container.BlueprintContainerImpl.run(BlueprintContainerImpl.java:269)[21:org.apache.aries.blueprint.core:1.4.2]
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)[:1.7.0_67]
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)[:1.7.0_67]
    at org.apache.aries.blueprint.container.ExecutorServiceWrapper.run(ExecutorServiceWrapper.java:106)[21:org.apache.aries.blueprint.core:1.4.2]
    at org.apache.aries.blueprint.utils.threading.impl.DiscardableRunnable.run(DiscardableRunnable.java:48)[21:org.apache.aries.blueprint.core:1.4.2]
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)[:1.7.0_67]
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)[:1.7.0_67]
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:178)[:1.7.0_67]
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:292)[:1.7.0_67]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)[:1.7.0_67]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)[:1.7.0_67]
    at java.lang.Thread.run(Thread.java:745)[:1.7.0_67]