public DirectoryWalker filter(Predicate<Path> pathFilter) {
    this.pathFilter = this.pathFilter.and(pathFilter);
    return this;
  }
Adds a filter to the walked paths.

@param pathFilter the filter. {@code pathFilter} returns {@code true} if the path should be
    accepted and {@code false} otherwise.
@return this
jib-core/src/main/java/com/google/cloud/tools/jib/filesystem/DirectoryWalker.java