Try with recursive strategy again.

.gitlab-ci.yml

 variables:
-  GIT_SUBMODULE_STRATEGY: none
+  GIT_SUBMODULE_STRATEGY: recursive
 
 stages:
   - build
 
-test:
+build:
   image: openjdk:8
   stage: build
   before_script:
-    - git submodule init
-    - git submodule sync
-    - cat .gitmodules
-    - cat .git/config
-    - ls -lah *
-    - rm -rf relast.preprocessor/*
-    - ls -lah *
-    - git submodule update --remote
+    # - git submodule init
+    # - git submodule sync
+    # - cat .gitmodules
+    # - cat .git/config
+    # - ls -lah *
+    # - rm -rf relast.preprocessor/*
+    # - ls -lah *
+    # - git submodule update --remote
     - ls -lah *
   script:
     - ./gradlew --no-daemon build