Each exclusion uses regular expression pattern matching, and must be separated by a new line.
        myapp/src/main/web/.*\.html
        myapp/src/main/web/.*\.jpeg
        myapp/src/main/web/.*\.gif
    

The example above illustrates that if only html/jpeg/gif files have been committed to the GitHub repository a build will not occur.
More information on regular expressions can be found here.