[Bug] FlatMapperIterator should be closed after usage

[qwtsc]

Bug Type (问题类型)

others (please edit later)

Before submit

• 我已经确认现有的 Issues 与 FAQ 中没有相同 / 重复问题 (I have confirmed and searched that there are no similar problems in the historical issue and documents)

Environment (环境信息)

• SonarQube block issue [java:S2095]

Connections, streams, files, and other classes that implement the Closeable interface or its super-interface, AutoCloseable, needs to be closed after use. Further, that close call must be made in a finally block otherwise an exception could keep the call from being made. Preferably, when class implements AutoCloseable, resource should be created using "try-with-resources" pattern and will be closed automatically.

Failure to properly close resources will result in a resource leak which could bring first the application and then perhaps the box the application is on to their knees.

Expected & Actual behavior (期望与实际表现)

        // Multiple steps, construct first step to iterator
        Iterator<Edge> edges = this.edgesOfVertexWithCount(source, firstStep);
        // Wrap steps to Iterator except last step
        for (int i = 1; i < stepNum - 1; i++) {
            EdgeStep currentStep = steps.get(i);
            edges = new FlatMapperIterator<>(edges, (edge) -> {
                Id target = ((HugeEdge) edge).id().otherVertexId();
                return this.edgesOfVertexWithCount(target, currentStep);
            });
        }

close FlatMapperIterator after usage

Vertex/Edge example (问题点 / 边数据举例)

No response

Schema [VertexLabel, EdgeLabel, IndexLabel] (元数据结构)

No response

[imbajin]

There are indeed some iterators in the current code that have not been finally closed.

U can confirm their lifecycle, if they are indeed legacy and may cause potential impact, you can help submit PR fixes (there should be some places in the class)

[qwtsc]

There are indeed some iterators in the current code that have not been finally closed.

U can confirm their lifecycle, if they are indeed legacy and may cause potential impact, you can help submit PR fixes (there should be some places in the class)

I have scanned the code, this is only case and u can review the above PR.