private DocumentReference validateDocumentReference(TemporaryImportedField importedField) {
        String referenceFieldName = importedField.referenceFieldName();
        DocumentReference reference = references.get().referenceMap().get(referenceFieldName);
        if (reference == null) {
            fail(importedField, "Reference field '" + referenceFieldName + "' not found");
        }
        return reference;
    }
Iterates all imported fields from schema parsing and validates and resolves them into concrete fields from referenced document types.

@author geirst
config-model/src/main/java/com/yahoo/schema/processing/ImportedFieldsResolver.java