Apache Cayenne: Merging fixed with dynamically supplied DataMaps into one ServerRuntime

My Application design contains fixed and dynamically DataMaps to connect to different (Oracle) DB instances/users. For simplicity i did split them into two different Cayenne Projects.

1. Create ServerRuntimeBuilder with fixed DataMap, build and query my customers table.

2. For every customer, load the dynamic DataMap with a second ServerRuntimeBuilder with the necessary modifications (change name and defaultschema):

   ...
   List<Customer> allCustomers = Customer.allCustomers(this.cayenneRuntime1.newContext());
   for (Customer customer : allCustomers) {
       final String dbPrefix = customer.getDbprefix();
   
       ServerRuntimeBuilder builder = ServerRuntime.builder();
       // load and modify DataMap
       builder.addConfig("ApacheCayenne/Data/cayenne-dynamicDomain.xml");
       builder.addModule(binder -> {
           binder.bind(DataMapLoader.class).to(MyDataMapLoader.class);
           ServerModule.contributeProperties(binder).put("CUSTOMER_PREFIX", dbPrefix);
       });
       ServerRuntime cayenneRuntime2 = builder.build();
       LOG.info("Initialized customer model " + customer + " prefix: " + customer.getDbprefix());
       // TODO Merge with cayenneRuntime1?
   }
   
   
   public class MyDataMapLoader extends XMLDataMapLoader {  
       @Inject
       private RuntimeProperties properties; 
       @Override
       public DataMap load(Resource configurationResource) throws CayenneRuntimeException {
           DataMap map = super.load(configurationResource);
           // Dynamically set name and default schema to map
           String dbPrefix = properties.get("CUSTOMER_PREFIX");
           map.setName(customer1.dbPrefix + "...")
           map.setDefaultSchema(customer1.dbPrefix + "...")
           return map;
       }
   }
   

And additionally an own ConfiguredDataSource implementation, that takes care about the JDBC connection URL and credentials. That part works fine so far.

My Problem: with this design i end up having 1 + n ServerRuntimes for every customer. But in the end i would want to have a singe ServerRuntime.

a) Is it possible merge these ServerRuntimes on the fly with Cayenne 4.0RC1 functions and future releases?

b) Do i need to read the dynamic maps with the help of cayenne-project library as described here. Modify and store every dynamic Project to the filesystem. After processing all my customers, create a final ServerRuntime with all the Cayenne Projects using the described way with an ExecutingMergerContext or with this Merging Multiple Projects?

ServerRuntime runtime = ServerRuntime.builder()
    .addConfig("com/example/cayenne-fixed-project.xml")
    .addConfig("org/foo/cayenne-dynamic-Customer1.xml")
    .addConfig("org/foo/cayenne-dynamic-Customer2.xml")
    .build();

Thanks in advance for helping me out.

I'd start runtime1 to get the config data, and then create runtime2 that contains both fixed and dynamic maps, and also a custom DataMap loader to dynamically rewrite name and schema:

ServerRuntime runtime2 = ServerRuntime.builder()
  .addConfig("com/example/cayenne-fixed-project.xml")
  .addConfig("org/foo/cayenne-dynamic-Customer1.xml")
  .addConfig("org/foo/cayenne-dynamic-Customer2.xml")
  .addModule(..)
  .build();

Just don't forget to shut down runtime1 when you are done with it, so you'll only have a single runtime at the end.