Pipeline from SCM jobs should have a fetch option

I created a declarative "pipeline from SCM" job. This pipeline defines parameters.

I have to trigger a build that will fail in order to configure the build (parameters). Only the second build will prompt parameters.

If I commit parameter changes in the JenkinsFile, same problem: I have to trigger a build that not prompt new options. Only the next build will have the right prompt parameters.

To correct this problem, "pipeline from SCM" jobs should have a "fetch" button, that would:

• fetch the JenkinsFile from the repository.
• validate the file syntax and configure the job.
• NOT trigger a build.