### Question:
SelectQuery extends AbstractQuery implements ParameterizedQuery, Select<T> { public void clearPrefetches() { metaData.clearPrefetches(); } SelectQuery();  SelectQuery(ObjEntity root);  SelectQuery(ObjEntity root, Expression qualifier);  SelectQuery(ObjEntity root, Expression qualifier, List<? extends Ordering> orderings);  SelectQuery(Class<T> rootClass);  SelectQuery(Class<T> rootClass, Expression qualifier);  SelectQuery(Class<T> rootClass, Expression qualifier, List<? extends Ordering> orderings);  SelectQuery(DbEntity root);  SelectQuery(DbEntity root, Expression qualifier);  SelectQuery(DbEntity root, Expression qualifier, List<? extends Ordering> orderings);  SelectQuery(String objEntityName);  SelectQuery(String objEntityName, Expression qualifier);  SelectQuery(String objEntityName, Expression qualifier, List<? extends Ordering> orderings); static SelectQuery<T> query(Class<T> rootClass); static SelectQuery<T> query(Class<T> rootClass, Expression qualifier); static SelectQuery<T> query(Class<T> rootClass, Expression qualifier, List<? extends Ordering> orderings); static SelectQuery<DataRow> dataRowQuery(Class<?> rootClass); static SelectQuery<DataRow> dataRowQuery(Class<?> rootClass, Expression qualifier); static SelectQuery<DataRow> dataRowQuery(Class<?> rootClass, Expression qualifier, List<Ordering> orderings); @Override List<T> select(ObjectContext context); @Override T selectOne(ObjectContext context); @Override T selectFirst(ObjectContext context); @Override void iterate(ObjectContext context, ResultIteratorCallback<T> callback); @Override ResultIterator<T> iterator(ObjectContext context); @Override ResultBatchIterator<T> batchIterator(ObjectContext context, int size); @Override QueryMetadata getMetaData(EntityResolver resolver); @Override void route(QueryRouter router, EntityResolver resolver, Query substitutedQuery); @Override SQLAction createSQLAction(SQLActionVisitor visitor); void initWithProperties(Map<String, ?> properties); SelectQuery<T> queryWithParameters(Map<String, ?> parameters); SelectQuery<T> queryWithParameters(Map<String, ?> parameters, boolean pruneMissing); SelectQuery<T> createQuery(Map<String, ?> parameters); void addOrdering(Ordering ordering); void addOrderings(Collection<? extends Ordering> orderings); void addOrdering(String sortPathSpec, SortOrder order); void removeOrdering(Ordering ordering); List<Ordering> getOrderings(); void clearOrderings(); boolean isDistinct(); void setDistinct(boolean distinct); void setSuppressDistinct(boolean suppressDistinct); void aliasPathSplits(String path, String... aliases); PrefetchTreeNode getPrefetchTree(); void setPrefetchTree(PrefetchTreeNode prefetchTree); void addPrefetch(PrefetchTreeNode prefetchElement); PrefetchTreeNode addPrefetch(String prefetchPath); void clearPrefetches(); void removePrefetch(String prefetchPath); boolean isFetchingDataRows(); void setFetchingDataRows(boolean flag); int getFetchOffset(); int getFetchLimit(); void setFetchLimit(int fetchLimit); void setFetchOffset(int fetchOffset); int getPageSize(); void setPageSize(int pageSize); void setStatementFetchSize(int size); int getStatementFetchSize(); void setQualifier(Expression qualifier); Expression getQualifier(); void andQualifier(Expression e); void orQualifier(Expression e); void setColumns(Collection<Property<?>> columns); void setColumns(Property<?>... columns); void setCanReturnScalarValue(boolean canReturnScalarValue); boolean canReturnScalarValue(); Collection<Property<?>> getColumns(); void setHavingQualifier(Expression qualifier); Expression getHavingQualifier(); void andHavingQualifier(Expression e); void orHavingQualifier(Expression e); static final String DISTINCT_PROPERTY; static final boolean DISTINCT_DEFAULT; }### Answer:
@Test public void testClearPrefetches() { query.addPrefetch("abc"); query.addPrefetch("xyz"); assertNotNull(query.getPrefetchTree()); query.clearPrefetches(); assertNull(query.getPrefetchTree()); }