public void push(FilePropertiesSpec filePropertiesSpec) {
    Preconditions.checkState(
        stack.size() < 3, "Error in file properties stack push, stacking over 3");
    stack.add(filePropertiesSpec);
    updateProperties();
  }
Add a new layer to the file properties stack. When adding a new layer, it is given highest
priority when resolving properties. All values are recalculated.
jib-cli/src/main/java/com/google/cloud/tools/jib/cli/buildfile/FilePropertiesStack.java