code: @Override
      protected ImmutableMap<Class<? extends QueryOptimizationProposal>, Class<? extends ProposalExecutor>>
      generateOptimizationConfigurationMap() {
          ImmutableMap.Builder<Class<? extends QueryOptimizationProposal>, Class<? extends ProposalExecutor>>
                  internalExecutorMapBuilder = ImmutableMap.builder();
          internalExecutorMapBuilder.putAll(super.generateOptimizationConfigurationMap());
          internalExecutorMapBuilder.putAll(optimizationConfiguration.generateOptimizationConfigurationMap());
  
          return internalExecutorMapBuilder.build();
      }
docs: Can be overloaded by sub-classes