[java] Fix template logic related to supportUrlQuery

Created by: bjorgvino

Generated models for arrays marked with uniqueItems: true (which end up as a Set<> in java) won't compile because the templates are in some places using .get(i) on the sets.

Also, when the supportUrlQuery property is present in the additionalProperties map the resulting value will be read using the constant SUPPORT_STREAMING instead of the key 'supportUrlQuery'.

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