[Java][RestTemplate][WebClient] Fix typo in comments

[fengkaijia]

Fix generateQueryUri method param queryParams mistype as queryParam in the comments. Previously IDE will have a "Cannot resolve symbol 'queryParam'" notification and red line on the typo.

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[fengkaijia]

cc @bbdouglas (2017/07) @sreeshas (2017/08) @jfiala (2017/08) @lukoyanov (2017/09) @cbornet (2017/09) @jeff9finger (2018/01) @karismann (2019/03) @Zomzog (2019/04) @lwlee2608 (2019/10) @nmuesch (2021/01)

[wing328]

Good catch. Thanks for the fix.