How to use Code Pipeline to continuously deploy to a CloudFormation Stack

I am trying to build a code pipeline to:

1. Take a github Java source project
2. Build it to generate a jar file
3. Use an sam-template.yml to deploy the jar

I can build the jar, ie I have stage 2 working. I assume stage 3 will involve invoking a sam-template to do the deployment. The template is part of the same github repo.

My question is: I cannot see how to supply the jar and template file to a third stage to do the deployment.

I attached three files below for information:

1. A build spec, which works but I cannot find the generated artifacts.
2. A json of the pipeline so far, generated by aws codepipeline get-pipeline
3. A copy of the sam-template.yml that will be used in Stage 3

1. buildspec.yml

version: 0.2

phases:
  install:
    commands:
      - echo Entered the install phase...
      - apt-get update -y
      - apt-get install -y maven
  build:
    commands:
      - echo Entered the build phase...
      - mvn package
  post_build:
    commands:
      - echo Entered the post_build phase...
artifacts:
  files:
    - server/harvest/target/harvest-1.0-SNAPSHOT.jar
  discard-paths: yes
secondary-artifacts:
  cf-config:
    files:
      - server/aws/sam-app/sam-template.yml
    discard-paths: yes
  jar-file:
    files:
      - server/harvest/target/harvest-1.0-SNAPSHOT.jar
    discard-paths: yes

2. codepipeline.json

{
    "pipeline": {
        "name": "<<Name>>",
        "roleArn": "arn:aws:iam::xxxxxxxx",
        "artifactStore": {
            "type": "S3",
            "location": "codepipeline-eu-west-1-xxxxxxx"
        },
        "stages": [
            {
                "name": "Source",
                "actions": [
                    {
                        "name": "Source",
                        "actionTypeId": {
                            "category": "Source",
                            "owner": "ThirdParty",
                            "provider": "GitHub",
                            "version": "1"
                        },
                        "runOrder": 1,
                        "configuration": {
                            "Branch": "master",
                            "OAuthToken": "****",
                            "Owner": "<<username>>",
                            "PollForSourceChanges": "false",
                            "Repo": "repo-name"
                        },
                        "outputArtifacts": [
                            {
                                "name": "SourceArtifact"
                            }
                        ],
                        "inputArtifacts": []
                    }
                ]
            },
            {
                "name": "Build",
                "actions": [
                    {
                        "name": "Build",
                        "actionTypeId": {
                            "category": "Build",
                            "owner": "AWS",
                            "provider": "CodeBuild",
                            "version": "1"
                        },
                        "runOrder": 1,
                        "configuration": {
                            "ProjectName": "Harvest"
                        },
                        "outputArtifacts": [
                            {
                                "name": "BuildArtifact"
                            }
                        ],
                        "inputArtifacts": [
                            {
                                "name": "SourceArtifact"
                            }
                        ]
                    }
                ]
            }
        ],
        "version": 3
    },
    "metadata": {
        "pipelineArn": "arn:aws:codepipeline:eu-west-1:xxxxxxxxx",
        "created": 1546780342.845,
        "updated": 1547288970.709
    }
}

3. sam-template.yml

AWSTemplateFormatVersion: '2010-09-09'
Description: AWS Serverless Spring Boot API - uk.co.pack::harvest
Globals:
  Api:
    EndpointConfiguration: REGIONAL
Outputs:
  HarvestApi:
    Description: URL for application
    Export:
      Name: HarvestApi
    Value: !Sub 'https://${ServerlessRestApi}.execute-api.${AWS::Region}.amazonaws.com/Prod/ping'
Parameters:
  amazonawsaccessKey:
    Type: String
  amazonawssecretkey:
    Type: String
  amazondynamodbendpoint:
    Type: String
  appid:
    Type: String
  url:
    Type: String
Resources:
  HarvestRatingsFunction:
    Properties:
      CodeUri: build/harvest-1.0-SNAPSHOT.jar
      Environment:
        Variables:
          AMAZON_AWS_ACCESSKEY: !Ref 'amazonawsaccessKey'
          AMAZON_AWS_SECRETKEY: !Ref 'amazonawssecretkey'
          AMAZON_DYNAMODB_ENDPOINT: !Ref 'amazondynamodbendpoint'
          IOS_APP_ID: !Ref 'appid'
          IOS_URL: !Ref 'url'
      Events:
        GetResource:
          Properties:
            Method: any
            Path: /{proxy+}
          Type: Api
      Handler: uk.co.pack.StreamLambdaHandler::handleRequest
      MemorySize: 512
      Policies: AWSLambdaBasicExecutionRole
      Runtime: java8
      Timeout: 60
    Type: AWS::Serverless::Function
  RatingsDbTable:
    Properties:
      AttributeDefinitions:
      - AttributeName: id
        AttributeType: S
      BillingMode: PROVISIONED
      KeySchema:
      - AttributeName: id
        KeyType: HASH
      ProvisionedThroughput:
        ReadCapacityUnits: '1'
        WriteCapacityUnits: '1'
      TableName: Review
    Type: AWS::DynamoDB::Table
Transform: AWS::Serverless-2016-10-31