If the Poll SCM check box under the Build Triggers section is selected, you can use the Filter for Poll SCM field to specify the directories or files you want Jenkins to check before starting a build. Any changes made to the files or directories that you specify in the Filter for Poll SCM field will trigger a build in Jenkins.
Directories and files must be specified in a comma-separated list and can use relative pathnames. For example, you could use:
src/com/my-company/main/my-file.java,src/com/webapp/my-file2.xml,src/com/*
where "src" is the immediate sub-folder under your stream or reference tree.
NOTE: If you select Poll SCM in the Build Triggers section of the Jenkins configuration page, but you do not specify any Filter for Poll SCM files or directories, then any files or directories you have specified in the Sub-path field are used as the filter for polling. In this case, changes made to elements in the sub-path will trigger a build in Jenkins.