Java Enhancement Proposal 227, titled Unicode 7.0, was created to indicate the need to update the appropriate APIs to support Unicode version 7.0. That version of Unicode was released on June 16, 2014. Previous to Java 9, Unicode version 6.2 was the latest version supported.
You can learn more about Unicode version 7.0.0 at the official specification page at: http://unicode.org/versions/Unicode7.0.0/.
At the time this book was published, the most recent Unicode standard was version 10.0.0, released on June 20, 2017. Interestingly, the Java 9 platform will support Unicode version 7.0.0, but not the more recent version 10.0.0 of the Unicode standard. In addition to the two Unicode specifications listed here, from version 7.0.0, ...
