@RestrictedApi(explanation = "Should only be called in tests", link = "",
      allowedOnPath = ".*/(.*/MasterRegistry.java|src/test/.*)")
  CompletableFuture<Set<ServerName>> getMasters() {
    return this
      .<GetMastersResponse> call(
        (c, s, d) -> s.getMasters(c, GetMastersRequest.getDefaultInstance(), d),
        r -> r.getMasterServersCount() != 0, "getMasters()")
      .thenApply(MasterRegistry::transformServerNames);
  }
Builds the default master address end point if it is not specified in the configuration.
<p/>
Will be called in {@code HBaseTestingUtility}.
hbase-client/src/main/java/org/apache/hadoop/hbase/client/MasterRegistry.java