* @param custom schema set customization
* @return owning schemaset, <code>null</code> if none
*/
private SchemasetCustom findSchemaset(SchemaElement schema, SchemasetCustom custom) {
LazyList childs = custom.getChildren();
SchemasetCustom owner = null;
String name = schema.getResolver().getName();
for (int i = 0; i < childs.size(); i++) {
Object child = childs.get(i);
if (child instanceof SchemasetCustom) {
SchemasetCustom schemaset = (SchemasetCustom)child;
if (schemaset.isInSet(name, schema)) {
SchemasetCustom match = findSchemaset(schema, schemaset);
if (match != null) {
if (owner == null) {
owner = match;
} else {
m_validationContext.addError("schema-set overlap on schema " + name + " (first match "