Looks like Flyway did support phoenix as mentioned in the release note of version 4.0
However, when I look at compatible databases of the latest build, Phoenix is not listed. Does it mean Phoenix support has been dropped?
From the Flyway 5.0.0 Release Notes:
Important note for EnterpriseDB, Vertica, SolidDB, Phoenix and Greenplum: Support for these databases has been kept back and will be integrated later in the Flyway 5.0 series. You can keep using Flyway 4.2.0 until then.
Looks like the code was removed in the initial Flyway 5.0 commit but, as of version 5.1.4, has yet to be reintegrated.