SPI loader and static method issue

[Cyrille Duret]

Hello,
I want to embedd neo4j in a bundle A, and create an graph database in a
bundle B.

Neo4j kernel artifact relies heavily on SPI mechanism for exposing config
properties so I use SPI Fly to mediate the java ServiceLoader :
<dependency>
  <groupId>org.apache.aries.spifly</groupId>
   <artifactId>org.apache.aries.spifly.dynamic.bundle</artifactId>
  <version>1.2.3</version>
</dependency>


My bundle A config :

<Embedd-Dependency>
..
*;groupId=org.neo4j;artifactId=neo4j-kernel;inline=META-INF/services/*,
..
</Embedd-Dependency>
<SPI-Provider>*</SPI-Provider>
<Export-Package>
..org.neo4j.configuration;version=${neo4j-version},
..</Export-Package>


My bundle B config :

<Import-Package>
..
org.neo4j.configuration;version=${neo4j-version},
..
</Import-Package>
<SPI-Consumer>*</SPI-Consumer>


In my B activator start method  :
import org.neo4j.configuration.LoadableConfig;
..
ServiceLoader<LoadableConfig> serviceLoader =
ServiceLoader.load(LoadableConfig.class);
Iterator<LoadableConfig> it = serviceLoader.iterator();
// I can see all exposed config from bundle A
while( it.hasNext() ) {
  final LoadableConfig config = it.next();
  System.out.println("-> "+config);
}

// The call from this static method does not return any config
List<LoadableConfig> configs = LoadableConfig.allConfigClasses();
System.out.println("configs from LoadableConfig => "+configs.size());


the org.neo4j.configuration.LoadableConfig.allConfigClasses method which is
embedded in A has the following implementation :
static List<LoadableConfig> allConfigClasses()
{
    return Iterators.stream( ServiceLoader.load( LoadableConfig.class
).iterator() ).collect( Collectors.toList() );
}

I do not understand why the allConfigClasses() method does not see the
exposed SPI services and why my ServiceLoader.load snippet code does.
I have noticed that if I added <SPI-Consumer>*</SPI-Consumer> to A, the
LoadableConfig.allConfigClasses does indeed work.

Anyone can explain me why the static method does not work in the first
place and why it does when adding <SPI-Consumer>*</SPI-Consumer> to A ??

thank you
Cyrille