An oolong is wilt in the sun but “fermented” in the shade. Proper fermentation of oolong requires rolling of the leaves. Something left to wither in the sun is a sun-dried tea, like mao cha for pu-erh. Even when an oolong looks green, it is still an oolong tea. Examples are green style tie guan yin, hairy crab, or “high mountain” oolongs from Taiwan. Someone who said that thing in the blog you read does not know about oolong at all. This is common place in tea blogs or forums in USA.
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