Upgrade rsocket-core to 1.0.0-RC2

Closes gh-23359

Author: rstoyanchev

build.gradle

@@ -41,7 +41,7 @@ ext {
 	log4jVersion         = "2.12.0"
 	nettyVersion         = "4.1.38.Final"
 	reactorVersion       = "Dysprosium-M3"
-	rsocketVersion       = "0.12.2-RC4"
+	rsocketVersion       = "1.0.0-RC2"
 	rxjavaVersion        = "1.3.8"
 	rxjavaAdapterVersion = "1.2.1"
 	rxjava2Version       = "2.2.10"