private void indexOnDocumentName(List<Schema> schemas) {
        documentNameToSearch.clear();
        for (Schema schema : schemas) {
            if (schema.getDocument() != null) {
                documentNameToSearch.put(schema.getDocument().getDocumentName(), schema);
            }
        }
    }
Removes and returns the first search from the move list which can now be added, or null if none
config-model/src/main/java/com/yahoo/schema/derived/SearchOrderer.java