Use `Optional.of` instead of `Optional.ofNullable` in `LegacyQueryUniverse`
Use `Optional.of` instead of `Optional.ofNullable` in `LegacyQueryUniverse`

Summary: I now have a better understanding of how this works. There's no way for this function to return `null`, and therefore we don't need to use `ofNullable`.

Reviewed By: bobyangyf

shipit-source-id: 9d66a340d65e6449694b88f29a7a6ef8d5052797

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