hg: jdk/submit: 8230681: Add @since tag to java.io.Serial

[joe.darcy at oracle.com]

Changeset: 1e3f58d409f7
Author:    darcy
Date:      2019-09-05 15:55 -0700
URL:       https://hg.openjdk.java.net/jdk/submit/rev/1e3f58d409f7

8230681: Add @since tag to java.io.Serial
Reviewed-by: lancea, bpb

! src/java.base/share/classes/java/io/Serial.java