[4.2] exists true on DatabaseSessionHandler insert
fix phpdoc block for Eloquent Model find method

add null
Merge pull request #6124 from dbwhddn10/patch-1

[4.2] Fix PHPDoc Block For Eloquent Model Find Method
Merge pull request #6099 from bashaus/add-exists-to-database-handler-on-insert-4.2

[4.2] Set Exists True On DatabaseSessionHandler
Cache the method name as well as the attribute for getMutators to avoid the cost of all the studly_case calls.