Fix TableView's existing key-value will never be updated

[BewareMyPower]

Fixes #486

Motivation

The emplace method of SynchronizedHashMap adopts the same semantics as https://en.cppreference.com/w/cpp/container/map/emplace, which inserts the key-value only when the key does not exist. TableViewImpl leverages this method to update the key-values, so it will never succeed. In addition, this method is not thread safe because if the key exists, an iterator will be returned to the caller, then the caller could use the iterator to modify the value without any synchronization.

Modifications

Add two new methods putIfAbsent and put and remove the emplace method.

• putIfAbsent: inserts the key-value only when the key does not exist and return the optional existing value
• put: inserts the key-value no matter if the key exists.

Then, replace the emplace call with put in TableViewImpl.

Verifying this change

testSimpleTableView is improved to verify the update case.