What is the test for determining whether a communication is a matter of public concern?

responsibilities." City of San Diego v. Roe, 543 U.S. 77, 84 (2004) (per curiam) (internal alteration omitted). The essence of the content inquiry is whether the "'main thrust' of the speech in question is essentially public in nature or private." Mitchell v. Hillsborough Cnty., 468 F.3d 1276, 1283 (11th Cir. 2006) (citations omitted).

In addition to the communication's content, "the employee's motivation and the chosen audience are among the many factors to be considered" in determining whether the communication is a matter of public concern. Johnson v. Multnomah Cnty., 48 F.3d 420, 425 (9th Cir. 1995).