In addxxx() functions of Mutation(Append, Delete, Increment and Put) and Query(Get and Scan), there are redundant Map#put() calls which could be removed to improve the performance.
For example, in Put#addColumn() and addImmutable(), after getting the cell list of the given family and add the cell into the list, the code puts (key=family, value=list) into familyMap.
In addColumn(), it is like
In addImmutable(), it is like
I think those put() for Map only take effect when getCellList(family) returns a new allocated ArrayList. When the list for a family already exist, put() for Map will update the value to the reference of the list, but actually, the reference of the list is not changed.
Those put() do not do any harm in terms of the correctness when they are here. But it could be removed to improve the performance. familyMap searches for key and set the new value and return the old value. Those operation take some time but actually are not needed.
The put() could be moved into Mutation#getCellList(family)