code: private List<ScmMaterialConfig> filterScmMaterials() {
          List<ScmMaterialConfig> scmMaterials = new ArrayList<>();
          for (MaterialConfig material : this) {
              if (material instanceof ScmMaterialConfig) {
                  scmMaterials.add((ScmMaterialConfig) material);
              }
          }
          return scmMaterials;
      }
docs: /*
  To two methods below are to avoid creating methods on already long Material interface with a No Op implementations.