### Question:
QueryMixin { public final <P> T join(Expression<P> target) { metadata.addJoin(JoinType.JOIN, target); return self; } QueryMixin();  QueryMixin(QueryMetadata metadata);  QueryMixin(QueryMetadata metadata, boolean expandAnyPaths);  QueryMixin(T self);  QueryMixin(T self, QueryMetadata metadata);  QueryMixin(T self, QueryMetadata metadata, boolean expandAnyPaths); T addJoin(JoinType joinType, Expression<?> target); T addFlag(QueryFlag queryFlag); T addJoinFlag(JoinFlag flag); T removeFlag(QueryFlag queryFlag); Expression<E> setProjection(Expression<E> e); Expression<?> setProjection(Expression<?>... o); @SuppressWarnings({"rawtypes", "unchecked"}) Expression<RT> convert(Expression<RT> expr, Role role); final T distinct(); final T from(Expression<?> arg); final T from(Expression<?>... args); final T fullJoin(Expression<?> target); final T fullJoin(Expression<P> target, Path<P> alias); final T fullJoin(CollectionExpression<?,P> target, Path<P> alias); final T fullJoin(MapExpression<?,P> target, Path<P> alias); final T fullJoin(SubQueryExpression<P> target, Path<?> alias); final QueryMetadata getMetadata(); final T getSelf(); final T groupBy(Expression<?> e); final T groupBy(Expression<?>... o); final T having(Predicate e); final T having(Predicate... o); final T innerJoin(Expression<P> target); final T innerJoin(Expression<P> target, Path<P> alias); final T innerJoin(CollectionExpression<?,P> target, Path<P> alias); final T innerJoin(MapExpression<?,P> target, Path<P> alias); final T innerJoin(SubQueryExpression<P> target, Path<?> alias); final boolean isDistinct(); final boolean isUnique(); final T join(Expression<P> target); final T join(Expression<P> target, Path<P> alias); final T join(CollectionExpression<?,P> target, Path<P> alias); final T join(MapExpression<?,P> target, Path<P> alias); final T join(SubQueryExpression<P> target, Path<?> alias); final T leftJoin(Expression<P> target); final T leftJoin(Expression<P> target, Path<P> alias); final T leftJoin(CollectionExpression<?,P> target, Path<P> alias); final T leftJoin(MapExpression<?,P> target, Path<P> alias); final T leftJoin(SubQueryExpression<P> target, Path<?> alias); final T limit(long limit); final T offset(long offset); final T on(Predicate condition); final T on(Predicate... conditions); @SuppressWarnings("unchecked") final T orderBy(OrderSpecifier<?> spec); final T orderBy(OrderSpecifier<?>... o); final T restrict(QueryModifiers modifiers); final T rightJoin(Expression<P> target); final T rightJoin(Expression<P> target, Path<P> alias); final T rightJoin(CollectionExpression<?,P> target, Path<P> alias); final T rightJoin(MapExpression<?,P> target, Path<P> alias); final T rightJoin(SubQueryExpression<P> target, Path<?> alias); final T set(ParamExpression<P> param, P value); final void setDistinct(boolean distinct); final void setSelf(T self); final void setUnique(boolean unique); final T where(Predicate e); final T where(Predicate... o); @Override final boolean equals(Object o); @Override int hashCode(); @Override String toString();  }### Answer:
@Test public void join() { DummyEntity e = Alias.alias(DummyEntity.class); DummyEntity e2 = Alias.alias(DummyEntity.class, "e2"); DummyEntity e3 = Alias.alias(DummyEntity.class, "e3"); DummyEntity e4 = Alias.alias(DummyEntity.class, "e4"); mixin.innerJoin($(e)); mixin.innerJoin($(e.getOther()),$(e2)); mixin.innerJoin($(e.getList()),$(e3)); mixin.innerJoin($(e.getList())); mixin.innerJoin($(e.getMap()),$(e4)); mixin.innerJoin($(e.getMap())); assertEquals(6, mixin.getMetadata().getJoins().size()); }