private List<ImmutableSDField> fieldsSettingLanguage(Schema schema) {
        return schema.allFieldsList().stream()
                     .filter(field -> ! field.isImportedField())
                     .filter(field -> field.containsExpression(SetLanguageExpression.class))
                     .toList();
    }
An indexing language script derived from a schema. An indexing script contains a set of indexing
statements, organized in a composite structure of indexing code snippets.

@author bratseth
config-model/src/main/java/com/yahoo/schema/derived/IndexingScript.java