DataWeave - Support 2.1.8
===========
Update: 2.1.8-OP-20200728

## Patches Release Notes

| Issue | Description |
|----------------|----------------|
|**SE-9379** |Fixes an issue that resulted in a `FileNotFoundException` error while executing an expression in large-batch scenarios, which was caused by prematurely closing the content stream.|
|**SE-10548**|Fixes `distinct` operation running out of memory with a large collection.|
|**SE-10638**|Fixes high CPU usage in transformation causes worker to stop processing.|
|**SE-10706**|Fixes an issue in which an expression used to display information with the Logger component failed in high-load scenarios.|
|**SE-10844**|Use `UTF-8` to load core modules as `Crypto::hashWith` was not working on Windows.|
|**SE-11246**|Close streams to avoid file leaks.|
|**SE-11527**|Support dynamic namespaces.|
|**SE-11410**|Fix logic for handling occurs control variables nested in structures for flatfile module.|
|**SE-11650**|Fixes ControlVal property in Cobol Copybook schema was ignored.|
|**SE-11664**|Fixes an inconsistent transformations called via a SOAP router when executed across Linux and Windows operating systems.|
|**SE-12035**|Support `java.util.Optional` as an expected `DataType` for the expression language.|
|**SE-12726**|Don't call to the `get()` function of a future.|
|**SE-12917**|Make string calculation of `UnsupportedTypeCoercionException` lazy.|
|**SE-12923**|Fixes memory issue while processing large payloads.|
|**SE-14754**|Update to latest `javax.mail` version which supports headers in `UTF-8`.|
|**DW-112**  |Security fix.|
|**SE-13423**|Flatfile writer can now handle dw keys as values.|
|**SE-15960**|Upgrade log4j dependency in Flatfile module.|