Make the ParquetLoader.inputFormatCache HashMap a WeakHashMap in order to free memory for long running processes that do not leverage caching
use a new string in order to enforce weak reference on the key
use a new string in order to enforce weak reference on the key
use a new string in order to enforce weak reference on the key
fix comment
fix comment, remove size
Merge pull request #204 from aaghevli/ParquetLoader.inputFormatCache

ParquetLoader.inputFormatCache as WeakHashMap