- Imported nifi-bom to nifi-commons and nifi-nar-bundles parent modules
- Removed explicit version and scope properties for dependencies declared in nifi-bom
- Added nifi-web-client implementation based on OkHttp
- Added WebClientServiceProvider Controller Service interface and implementation
- Corrected comments and added unmodifiableMap wrapper
- Added getHeaderNames() and corrected ProxyContext comments
This closes#6268
Signed-off-by: Paul Grey <greyp@apache.org>