When I call this Arquillian Graphene's method in method annotated with TestNG @BeforeMethod, then it is not possible to get Graphene's configuration.

On this line, configuration.get() returns null.

The configuration should be retrieved from Instance<GrapheneConfiguration>. However, it is not.

When I compare this to JUnit @Before, I came to this:
At ManagerImpl.java here, the configuration is retrieved from context ClassContextImpl.

However, that context is not marked as active when executing from TestNG (among the others contexts).