当gremlin path（）函数与.toList（）或.list（l）（l是空的ArrayList）一起使用时发生异常
org.apache.tinkerpop.gremlin.driver.exception.ResponseException: org.janusgraph.graphdb.vertices.CacheVertex cannot be cast to org.apache.tinkerpop.gremlin.structure.Edge
at org.apache.tinkerpop.gremlin.driver.Handler$GremlinResponseHandler.channelRead0(Handler.java:246) ~[gremlin-driver-3.3.3.jar:3.3.3]
at org.apache.tinkerpop.gremlin.driver.Handler$GremlinResponseHandler.channelRead0(Handler.java:197) ~[gremlin-driver-3.3.3.jar:3.3.3]
at io.netty.channel.SimpleChannelInboundHandler.channelRead(SimpleChannelInboundHandler.java:105) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at org.apache.tinkerpop.gremlin.driver.Handler$GremlinSaslAuthenticationHandler.channelRead0(Handler.java:123) ~[gremlin-driver-3.3.3.jar:3.3.3]
at org.apache.tinkerpop.gremlin.driver.Handler$GremlinSaslAuthenticationHandler.channelRead0(Handler.java:67) ~[gremlin-driver-3.3.3.jar:3.3.3]
at io.netty.channel.SimpleChannelInboundHandler.channelRead(SimpleChannelInboundHandler.java:105) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:102) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at org.apache.tinkerpop.gremlin.driver.handler.WebSocketClientHandler.channelRead0(WebSocketClientHandler.java:94) ~[gremlin-driver-3.3.3.jar:3.3.3]
at io.netty.channel.SimpleChannelInboundHandler.channelRead(SimpleChannelInboundHandler.java:105) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:310) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:284) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1434) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:965) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:163) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:647) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:582) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:499) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:461) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:884) ~[netty-all-4.1.25.Final.jar:4.1.25.Final]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_172]