Firebase 6.2.0 Version Number/GUIDS

PiperOrigin-RevId: 255691391

Author: ryanmeier

cpp_sdk_version.json

@@ -1,5 +1,5 @@
 {
-  "released": "6.1.0",
-  "stable": "6.1.0",
-  "head": "6.1.0"
+  "released": "6.2.0",
+  "stable": "6.2.0",
+  "head": "6.2.0"
 }