Null value not allowed as an environment variable: DOCKER_CONTAINER_ID

[cpfeiffer]

• docker-plugin 1.1.8
• matrix project plugin 1.1.4
• build name and description setter 2.0.3
• token macro plugin 2.10
• Jenkins 2.190.2

This probably happens early when there is no node yet, so getEnvironment() should make this an empty string in that case.
Actually this happens at the end of the build. We configured
Set build name before build starts and NOT
Set build name after build ends, so I don't quite understand why this happens in endBuild().

java.lang.IllegalArgumentException: Null value not allowed as an environment variable: DOCKER_CONTAINER_ID
	at hudson.EnvVars.put(EnvVars.java:379)
	at io.jenkins.docker.DockerComputer.getEnvironment(DockerComputer.java:51)
	at jenkins.model.CoreEnvironmentContributor.buildEnvironmentFor(CoreEnvironmentContributor.java:30)
	at hudson.model.Run.getEnvironment(Run.java:2350)
	at hudson.model.AbstractBuild.getEnvironment(AbstractBuild.java:864)
	at org.jenkinsci.plugins.tokenmacro.TokenMacro.expandAll(TokenMacro.java:220)
	at org.jenkinsci.plugins.tokenmacro.TokenMacro.expandAll(TokenMacro.java:207)
	at org.jenkinsci.plugins.buildnamesetter.Executor.evaluateMacro(Executor.java:75)
	at org.jenkinsci.plugins.buildnamesetter.Executor.setName(Executor.java:30)
	at org.jenkinsci.plugins.buildnamesetter.BuildNameSetter$2.endBuild(BuildNameSetter.java:117)
	at hudson.matrix.MatrixBuild$MatrixBuildExecution.post2(MatrixBuild.java:433)
	at hudson.model.AbstractBuild$AbstractBuildExecution.post(AbstractBuild.java:635)
	at hudson.model.Run.execute(Run.java:1840)
	at hudson.matrix.MatrixBuild.run(MatrixBuild.java:323)
	at hudson.model.ResourceController.execute(ResourceController.java:97)
	at hudson.model.Executor.run(Executor.java:429)

[pjdarton]

Code changes went into released of docker-plugin version 1.1.9