Flink x.x is a temporary name for alibaba flink branch and is for test purpose only. The final name should be discussed further and will be changed before pushing the code to flink github.
These release notes discuss important aspects, such as configuration, behavior, or dependencies, that changed between Flink 1.5.1 and Flink x.x. Please read these notes carefully if you are planning to upgrade your Flink version to x.x.
Flink x.x is a version donated by Alibaba with new features and changes focusing on improving the performance, usability and stability of Apache Flink.