spanner: release v1.2.0

Change-Id: I373c02d0b4c814510c59f8423437c95eaab1c651
Reviewed-on: https://code-review.googlesource.com/c/gocloud/+/50950
Reviewed-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Knut Olav Løite <koloite@gmail.com>
Reviewed-by: Shanika Kuruppu <skuruppu@google.com>

internal/version/version.go

@@ -26,7 +26,7 @@ import (
 
 // Repo is the current version of the client libraries in this
 // repo. It should be a date in YYYYMMDD format.
-const Repo = "20200123"
+const Repo = "20200128"
 
 // Go returns the Go runtime version. The returned string
 // has no whitespace.

spanner/CHANGES.md

@@ -1,5 +1,22 @@
 # Changes
 
+## v1.2.0
+
+- Support tracking stacktrace of sessionPool.take() that allows the user
+  to instruct the session pool to keep track of the stacktrace of each
+  goroutine that checks out a session from the pool. This is disabled by
+  default, but it can be enabled by setting
+  `SessionPoolConfig.TrackSessionHandles: true`.
+- Add resource-based routing that includes a step to retrieve the
+  instance-specific endpoint before creating the session client when
+  creating a new spanner client. This is disabled by default, but it can
+  be enabled by setting `GOOGLE_CLOUD_SPANNER_ENABLE_RESOURCE_BASED_ROUTING`.
+- Make logger configurable so that the Spanner client can now be configured to
+  use a specific logger instead of the standard logger.
+- Support encoding custom types that point back to supported basic types.
+- Allow decoding Spanner values to custom types that point back to supported
+  types.
+
 ## v1.1.0
 
 - The String() method of NullString, NullTime and NullDate will now return