What is the test for a retaliation claim under the First Amendment?

"A plaintiff asserting a First Amendment retaliation claim must establish that: (1) his speech or conduct was protected by the First Amendment; (2) the defendant took adverse action against him; and (3) there was a causal connection between this adverse action and the protected speech." Matthews v. City of New York, 779 F.3d 167, 172 (2d Cir. 2015) (internal quotation marks omitted).