Major Description
Based on the design doc, we need to split the operator tree of a work in SparkWork if the work is connected to multiple child works. The way splitting the operator tree is performed by cloning the original work and removing unwanted branches in the operator tree. Please refer to the design doc for details.
This process should be done right before we generate SparkPlan. We should have a utility method that takes the orignal SparkWork and return a modified SparkWork.
This process should also keep the information about the original work and its clones. Such information will be needed during SparkPlan generation (HIVE-8437).
