Adapt QueryByExampleExecutor API changes. [DATAJPA-1110]

[spring-projects-issues]

Christoph Strobl opened DATAJPA-1110 and commented

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Issue Links:

• DATACMNS-1058 QueryByExampleExecutor.find one should return Optional<S>
  ("depends on")

Referenced from: pull request #201, and commits 1f9e575, c02f444, efac93c, 62772e8, 84ce56d