Hanyu Zheng

@snuyanzin can you help me do another code review. Thank you.

> This query fails with NullPointerException > > ```sql > SELECT map_union(MAP[1, 2], MAP[CAST(NULL AS INT), 3]); > ``` key = CAST(NULL AS INT) is ok now.

@snuyanzin rebased and add Chinese description

@flinkbot run azure

@flinkbot run azure

@snuyanzin , do you know why test_ci misc report error?

@snuyanzin solve all comments and achieve CommonCollectionInputTypeStrategy.

@snuyanzin do you think it is ok now? I let CommonMapInputTypeStrategy and CommonArrayInputTypeStrategy as subclass extends CommonCollectionInputTypeStrategy.

`Returns a map created by merging at least one map. These maps should have a common map type. If there are overlapping keys, the value from 'map2' will overwrite the...

@snuyanzin support varargs now