Update to use Go 1.15.

With the release of Go 1.16, we now only support Go 1.15 and higher, as
per our support policy. Update the README to note this and our
automation to use 1.15 instead of 1.16.

.circleci/config.yml

@@ -16,13 +16,13 @@ commands:
 jobs:
   "docker-go114 build":
     docker:
-      - image: docker.mirror.hashicorp.services/circleci/golang:1.14
+      - image: docker.mirror.hashicorp.services/circleci/golang:1.15
     steps:
       - get_dependencies
       - run: go build ./...
   "docker-go114 test":
     docker:
-      - image: docker.mirror.hashicorp.services/circleci/golang:1.14
+      - image: docker.mirror.hashicorp.services/circleci/golang:1.15
         environment:
           TF_ACC_TERRAFORM_VERSION: "0.12.26"
     parameters:
@@ -44,19 +44,19 @@ jobs:
           path: << parameters.test_results >>
   "docker-go114 vet":
     docker:
-      - image: docker.mirror.hashicorp.services/circleci/golang:1.14
+      - image: docker.mirror.hashicorp.services/circleci/golang:1.15
     steps:
       - get_dependencies
       - run: go vet ./...
   "docker-go114 gofmt":
     docker:
-      - image: docker.mirror.hashicorp.services/circleci/golang:1.14
+      - image: docker.mirror.hashicorp.services/circleci/golang:1.15
     steps:
       - get_dependencies
       - run: ./scripts/gofmtcheck.sh
   "docker-go114 release":
     docker:
-      - image: docker.mirror.hashicorp.services/circleci/golang:1.14
+      - image: docker.mirror.hashicorp.services/circleci/golang:1.15
     steps:
       - add_ssh_keys:
           fingerprints:

.go-version

@@ -1 +1 @@
-1.14.9
+1.15.8

README.md

@@ -16,7 +16,7 @@ When running provider tests, Terraform 0.12.26 or later is needed for version 2.
 
 The Terraform Plugin SDK is built in Go, and uses the [support policy](https://golang.org/doc/devel/release.html#policy) of Go as its support policy. The two latest major releases of Go are supported by the SDK.
 
-Currently, that means Go **1.14** or later must be used when building a provider with the SDK.
+Currently, that means Go **1.15** or later must be used when building a provider with the SDK.
 
 ## Getting Started
 

go.mod

@@ -1,6 +1,6 @@
 module github.com/hashicorp/terraform-plugin-sdk/v2
 
-go 1.14
+go 1.15
 
 require (
 	cloud.google.com/go v0.61.0 // indirect