liquibase-core/src/main/java/liquibase/structure/DatabaseObjectCollection.java
public <DatabaseObjectType extends DatabaseObject> Set<DatabaseObjectType> get(Class<DatabaseObjectType> type) {

        Set<DatabaseObject> returnSet = new HashSet<>();

        Map<String, Set<DatabaseObject>> allFound = cache.get(type);
        if (allFound != null) {
            for (Set<DatabaseObject> objects : allFound.values()) {
                returnSet.addAll(objects);
            }
        }

        return (Set<DatabaseObjectType>) Collections.unmodifiableSet(returnSet);
    }
public <DatabaseObjectType extends DatabaseObject> Set<DatabaseObjectType> get(Class<DatabaseObjectType> type) {

        Set<DatabaseObject> returnSet = new HashSet<>();

        Map<String, Set<DatabaseObject>> allFound = cache.get(type);
        if (allFound != null) {
            for (Set<DatabaseObject> objects : allFound.values()) {
                returnSet.addAll(objects);
            }
        }

        return (Set<DatabaseObjectType>) Collections.unmodifiableSet(returnSet);
    }
Returns all objects of the given type that are already included in this snapshot.