[3.0.0] running in docker needs some love

[bsdkurt]

Description

3.0.0 branch run-in-docker.sh and docker-entrypoint.sh scripts need to be updated.

Swagger-codegen version

3.0.0

Command line used for generation

$ ./run-in-docker.sh mvn package
++ dirname ./run-in-docker.sh
<snip>
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.5.1:compile (default-compile) on project swagger-codegen: Fatal error compiling: invalid target release: 1.8 -> [Help 1]

and after run-in-docker.sh is fixed you will this this issue:

$ ./run-in-docker.sh generate -i test_swagger.yaml -l java -o /gen/out/test-client
++ dirname ./run-in-docker.sh
+ cd .
+ maven_cache_repo=/home/kurt/.m2/repository
+ mkdir -p /home/kurt/.m2/repository
++ id -u
++ id -g
+ docker run --rm -it -w /gen -e GEN_DIR=/gen -e MAVEN_CONFIG=/var/maven/.m2 -u 1001:1001 -v /home/kurt/swagger-codegen:/gen -v /home/kurt/.m2/repository:/var/maven/.m2/repository --entrypoint /gen/docker-entrypoint.sh maven:3-jdk-8 generate -i test_swagger.yaml -l java -o /gen/out/test-client
/gen/docker-entrypoint.sh: line 23: exec: generate: not found

Steps to reproduce

try to use run-in-docker.sh in 3.0 to build and generate a client

Suggest a fix/enhancement

#7679

[HugoMario]

fix related to this issue has been merged, so closing it out.