private void fail(TemporaryImportedField importedField, String msg) {
        throw new IllegalArgumentException("For " + schema + ", import field '" +
                                           importedField.fieldName() + "': " + msg);
    }
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