groovy.lang.MissingPropertyException: No such property: GIT_PASSWORD for class: groovy.lang.Binding - groovy

Question

I have checked all the topics on the same mistake, tried everything, and yet I was unable to find anything to help me solving my issue.
my code builds a docker container, starts a flask application and run a python script, run tests and then should merge Master. The code is the following :
pipeline {
agent any
stages {
stage('Master merging'){
steps{
script{
passwordVariable = 'password'
usernameVariable = 'unsername'
// Variables for input
if(env.BRANCH_NAME == 'features'||env.BRANCH_NAME == 'main'){
sh 'git checkout origin/features'
sh 'git pull'
sh 'git remote update'
sh 'git fetch'
sh 'git checkout origin/main'
sh 'git merge origin/features'
withCredentials([usernamePassword(credentialsId : 'GitHub', passwordVariable:'GIT_PASSWORD', usernameVariable:'GIT_USERNAME')]){
sh "git push http://${GIT_USERNAME}:${GIT_PASSWORD}#github.com/Username/Repo.git"
}
}}
}
}
}
}
when I arrive to stage('master merging'), I have the following mistake
Masking supported pattern matches of $GIT_PASSWORD
[Pipeline] {
[Pipeline] }
[Pipeline] // withCredentials
[Pipeline] }
[Pipeline] // script
[Pipeline] }
[Pipeline] // stage
[Pipeline] stage
[Pipeline] { (container shutdown)
Stage "container shutdown" skipped due to earlier failure(s)
[Pipeline] }
[Pipeline] // stage
[Pipeline] }
[Pipeline] // withEnv
[Pipeline] }
[Pipeline] // node
[Pipeline] End of Pipeline
groovy.lang.MissingPropertyException: No such property: GIT_PASSWORD for class: groovy.lang.Binding
at groovy.lang.Binding.getVariable(Binding.java:63)
Thanks a lot in advance for your help :)

Answer 1

I have an answer :)
Prerequisites : create a credential on Manage jenkins -> Manage credentials -> jenkins -> Global credentials (unrestricted) -> username with password. Inquire github username as username and Personal access token as password. ID is up to you.
Code :
stage('Master merging'){
steps{
script{
// Variables for input
if(env.BRANCH_NAME == 'features'||env.BRANCH_NAME == 'main'){
sh 'git checkout features'
sh 'git pull'
sh 'git remote update'
sh 'git fetch'
sh 'git checkout origin/main'
sh 'git merge features'
sh "git config user.email \"GITHUB EMAIL\""
sh "git config user.name \"GITHUB USERNAME\""
withCredentials([gitUsernamePassword(credentialsId:'ID you inquired in credentials')]) {
sh 'git push https://github.com/Username/Repo.git'
}
}
}
}
}