private String createPath(final String parent, final String child) {
        if (parent == null || parent.isEmpty()) {
            return child;
        }
        return parent + "/" + child;
    }
Prunes the node path for GitRepo exports. Removes everything in the rootPath
from the nodePath if the rootPath matches the start of the nodePath.
@param rootPath Can be null, in which case this function just returns nodePath.
                Otherwise, the list of items to prune from the start of nodePath.
@param nodePath The node path to prune.
@return The pruned nodePath.
stroom-importexport/stroom-importexport-impl/src/main/java/stroom/importexport/impl/ImportExportSerializerImpl.java