anchor.diff:  ARG SPARK_VERSION=3.1.2
   
   # stage.1 graphene
  -FROM ubuntu:18.04 AS graphene
  +FROM ubuntu:20.04 AS graphene
   ARG GRAPHENE_BRANCH=branch-1.2-rc1
   RUN env DEBIAN_FRONTEND=noninteractive apt-get update && \
       env DEBIAN_FRONTEND=noninteractive apt-get install -y \
  
positive.code: 
  
  # stage.4 ppml
  FROM ubuntu:18.04
  ARG BIGDL_VERSION
  ARG SPARK_VERSION
  ARG SCALA_VERSION=2.12
  
negative.code: RUN for f in $(find /graphene/Runtime -type l); do cp --remove-destination $(realpath $f) $f; done
  
  # stage.2 jdk & scala & flink
  FROM ubuntu:20.04 as flink
  ARG FLINK_VERSION=1.11.3
  ARG SCALA_VERSION=2.12
  ARG SCALA_SUB_VERSION_NUM=10
  