Reproduce problem with https://github.com/terraform-providers/terraform-provider-azurerm/pull/4616

terraform_azure_create_mongodb_with_throughput.go

package main

import (
	"context"
	"fmt"
	"log"
	"os"
	"strconv"

	"github.com/Azure/azure-sdk-for-go/services/cosmos-db/mgmt/2015-04-08/documentdb"
	"github.com/Azure/go-autorest/autorest/azure"
	"github.com/Azure/go-autorest/autorest/azure/auth"
)

const (
	resourceGroup  = "resourceGroup"
	subscriptionID = "subscriptionID"
	accountName    = "accountName"
	azureAuthFile  = `azure.auth`
)

func main() {
	err := os.Setenv("AZURE_AUTH_LOCATION", azureAuthFile)
	if err != nil {
		log.Fatal(err)
	}

	authorizer, err := auth.NewAuthorizerFromFile(azure.PublicCloud.ResourceManagerEndpoint)
	if err != nil {
		log.Fatal(err)
	}

	client := documentdb.NewDatabaseAccountsClient(subscriptionID)
	client.Authorizer = authorizer

	ctx := context.Background()

	testDbName1 := "test1"
	err = createDbWithThroughput(ctx, client, testDbName1, 400)
	if err != nil {
		log.Fatalf("%+v", err)
	}

	resp, err := client.GetMongoDBDatabase(ctx, resourceGroup, accountName, testDbName1)
	if err != nil {
		log.Fatalf("Error making get request for Cosmos Mongo Database %s (Account %s): %+v", testDbName1, accountName, err)
	}

	log.Printf("Response from first DB: %+v", resp)

	testDbName2 := "test2"
	err = updateDbWithThrougphut(ctx, client, testDbName2, 400)
	if err != nil {
		log.Fatalf("%+v", err)
	}

	resp, err = client.GetMongoDBDatabase(ctx, resourceGroup, accountName, testDbName2)
	if err != nil {
		log.Fatalf("Error making get request for Cosmos Mongo Database %s (Account %s): %+v", testDbName2, accountName, err)
	}

	log.Printf("Response from second DB: %+v", resp)
}

func createDbWithThroughput(ctx context.Context, client documentdb.DatabaseAccountsClient, dbName string, throughput int) error {
	throughputStr := strconv.Itoa(throughput)

	db := documentdb.MongoDBDatabaseCreateUpdateParameters{
		MongoDBDatabaseCreateUpdateProperties: &documentdb.MongoDBDatabaseCreateUpdateProperties{
			Resource: &documentdb.MongoDBDatabaseResource{
				ID: &dbName,
			},
			Options: map[string]*string{
				"x-ms-offer-throughput": &throughputStr,
			},
		},
	}

	future, err := client.CreateUpdateMongoDBDatabase(ctx, resourceGroup, accountName, dbName, db)
	if err != nil {
		return fmt.Errorf("Error issuing create/update request for Cosmos Mongo Database %s (Account %s): %+v", dbName, accountName, err)
	}

	if err = future.WaitForCompletionRef(ctx, client.Client); err != nil {
		return fmt.Errorf("Error waiting on create/update future for Cosmos Mongo Database %s (Account %s): %+v", dbName, accountName, err)
	}

	return nil
}

func updateDbWithThrougphut(ctx context.Context, client documentdb.DatabaseAccountsClient, dbName string, throughput int) error {
	throughputInt32 := int32(throughput)

	db := documentdb.MongoDBDatabaseCreateUpdateParameters{
		MongoDBDatabaseCreateUpdateProperties: &documentdb.MongoDBDatabaseCreateUpdateProperties{
			Resource: &documentdb.MongoDBDatabaseResource{
				ID: &dbName,
			},
			Options: map[string]*string{},
		},
	}

	future, err := client.CreateUpdateMongoDBDatabase(ctx, resourceGroup, accountName, dbName, db)
	if err != nil {
		return fmt.Errorf("Error issuing create/update request for Cosmos Mongo Database %s (Account %s): %+v", dbName, accountName, err)
	}

	if err = future.WaitForCompletionRef(ctx, client.Client); err != nil {
		return fmt.Errorf("Error waiting on create/update future for Cosmos Mongo Database %s (Account %s): %+v", dbName, accountName, err)
	}

	throughputParameters := documentdb.ThroughputUpdateParameters{
		ThroughputUpdateProperties: &documentdb.ThroughputUpdateProperties{
			Resource: &documentdb.ThroughputResource{
				Throughput: &throughputInt32,
			},
		},
	}

	throughputFuture, err := client.UpdateMongoDBDatabaseThroughput(ctx, resourceGroup, accountName, dbName, throughputParameters)
	if err != nil {
		return fmt.Errorf("Error setting Throughput for Cosmos MongoDB Database %s (Account %s): %+v", dbName, accountName, err)
	}

	if err = throughputFuture.WaitForCompletionRef(ctx, client.Client); err != nil {
		return fmt.Errorf("Error waiting on ThroughputUpdate future for Cosmos Mongo Database %s (Account %s): %+v", dbName, accountName, err)
	}

	return nil
}