Using getRequiredAdapter in RedisQueryEngine to avoid NPE

[junghoon-vans]

The getAdapter used by the RedisQueryEngine logic to get the adapter can return null.
To avoid this, we can use getRequiredAdapter.

[mp911de]

Did you encounter a NPE or how did you find out about the issue?

[junghoon-vans]

@mp911de I didn't experience any NPEs myself, I just thought I should fix anything in the source code that might cause an error.

I'm currently working on creating a Spring Data Implementation, and in the process I came across this and decided to open an issue.

[mp911de]

Alright, thanks for the detail.