Converting a Freestyle project to a Declarative Pipeline

```
@Extension
public class ShellConverter extends SingleTypedConverter<Shell>
    @Override
    public boolean convert( ConverterRequest request, ConverterResult result, Object target )
    {
      Shell shell = (Shell) target;
      /* Do some work to generate a new stage . . . */
      ModelASTStage stage = new ModelASTStage( this );
      // use a utility method to add the stage to the pipeline model
      ModelASTUtils.addStage( request.getModelASTPipelineDef(), stage);

      // true for success, false for failure
      return true;
    }
```
▼

```
@Extension
public class ShellConverter extends SingleTypedConverter<Shell>
{
  @Override
  public boolean convert (ConerterRequest request, ConverterRequest result, Object target )
    {
        Shell shell = (Shell) target;
        ModelASTStage stage = new ModelASTStage( this );
        int stageNumber = request.getAndIncrement( SHELL_NUMBER_KEY );  (1)
        stage.setName( "Shell script " + stageNumber );
        ModelASTBranch branch = new ModelASTBranch( this );  (2)
        stage.setBranches( Arrays.asList( branch ) );  (3)
        ModelASTStep step = new ModelASTStep( this );  (4)
        step.setName( "sh" );  (5)
        ModelASTSingleArgument singleArgument = new ModelASTSingleArgument( this );
        singleArgument.setValue( ModelASTValue.fromConstant( shell.getCommand(), this ) ); (6)
        step.setArgs( singleArgument );
        ModelASTUtils.wrapBranch(result, step, branch); (7)
        ModelASTUtils.addStage(result.getModelASTPipelineDef(), stage); (8)
        return true;
    }
}
```
▼

```
// This was to not have the config-file-provider plugin as a required dependency
// But you can use (as you use your plugin)
@OptionalExtension(requirePlugins = { "config-file-provider" })
public class ConfigFileBuildWrapperConverter extends SingleTypedConverter<ConfigFileBuildWrapper>
{
    private Logger LOGGER = LoggerFactory.getLogger( ConfigFileBuildWrapperConverter.class );

    @Override
    public boolean convert(ConverterRequest request, ConverterResult result, Object target)
    {
        ConfigFileBuildWrapper configFileBuildWrapper = (ConfigFileBuildWrapper) target;
        if(configFileBuildWrapper.getManagedFiles() == null || configFileBuildWrapper.getManagedFiles().isEmpty() )
        {
            return true;
        }

        result.addWrappingTreeStep( () -> build( configFileBuildWrapper) ); (1)
        return true;
    }

    private ModelASTTreeStep build(ConfigFileBuildWrapper configFileBuildWrapper) {
        ModelASTTreeStep configFileProvider = new ModelASTTreeStep( this );

        configFileProvider.setName( "configFileProvider" );
        ModelASTSingleArgument singleArgument = new ModelASTSingleArgument( null );
        configFileProvider.setArgs( singleArgument );

        ManagedFile managedFile = configFileBuildWrapper.getManagedFiles().get( 0 ); (2)
        StringBuilder gstring = new StringBuilder( "[configFile(fileId:'" );
        gstring.append( managedFile.getFileId());
        gstring.append( "', targetLocation: '" );
        gstring.append( managedFile.getTargetLocation() );
        gstring.append( "')]" );
        singleArgument.setValue( ModelASTValue.fromGString( gstring.toString(), this ) );


        return configFileProvider;
    }
}
```
▼

```
@Extension
public class ArtifactArchiverConverter extends SingleTypedConverter<ArtifactArchiver> {
    @Override
    public boolean convert(ConverterRequest request, ConverterResult result, Object target) {
        ArtifactArchiver artifactArchiver = (ArtifactArchiver) target;
        ModelASTBuildCondition buildCondition;
        if(artifactArchiver.isOnlyIfSuccessful()) { (1)
            buildCondition = ModelASTUtils.buildOrFindBuildCondition( result.getModelASTPipelineDef(), "success" );
        } else {
            buildCondition = ModelASTUtils.buildOrFindBuildCondition( result.getModelASTPipelineDef(), "always" );
        }
        ModelASTStep archiveArtifacts = ModelASTUtils.buildGenericStep(artifactArchiver, this);
        ModelASTUtils.addStep(buildCondition, archiveArtifacts); (2)
        return true;
    }
}
```
▼

```
@OptionalExtension(requirePlugins = { "git"})
public class GitScmConverter extends SingleTypedConverter<GitSCM>
{
  @Override
  public boolean convert(ConverterRequest request, ConverterResult result, Object target)
    {
        List<UserRemoteConfig> repoList = ( (GitSCM) target ).getUserRemoteConfigs();
        if(repoList.isEmpty()){
            return true;
        }
        ModelASTStage stage = new ModelASTStage( this ); (1)
        stage.setName( "Checkout Scm" );
        List<ModelASTStep> steps = new ArrayList<>(); (2)
        // a step will be created per remote repository
        for( UserRemoteConfig userRemoteConfig : repoList) (3)
        {
            ModelASTStep git = new ModelASTStep( null ); (4)
            git.setName( "git" );

            Map<ModelASTKey, ModelASTValue> args = new HashMap<>();
            {
                ModelASTKey url = new ModelASTKey( this ); (5)
                url.setKey( "url" );
                ModelASTValue urlValue = ModelASTValue.fromConstant( userRemoteConfig.getUrl(), this );
                args.put( url, urlValue );
            } (6)

            ...

            ModelASTNamedArgumentList stepArgs = new ModelASTNamedArgumentList( null);  (7)
            stepArgs.setArguments( args );
            git.setArgs( stepArgs );
            steps.add( git );
        }

        ModelASTBranch branch = new ModelASTBranch( this ); (8)
        branch.setSteps(steps);
        stage.setBranches( Arrays.asList( branch ) );
        ModelASTUtils.addStage(result.getModelASTPipelineDef(), stage ); (9)
        return true;
    }
}
```
▼

```
@Extension
public class TimerTriggerConverter extends SingleTypedConverter<TimerTrigger>
{
    @Override
    public boolean convert(ConverterRequest request, ConverterResult result, Object target)
    {
        TimerTrigger timerTrigger = (TimerTrigger) target;

        String cronValue = timerTrigger.getSpec();
        ModelASTTrigger modelASTTrigger = new ModelASTTrigger( this ); (1)
        modelASTTrigger.setName( "cron" );
        modelASTTrigger.setArgs( Arrays.asList(ModelASTValue.fromConstant( cronValue, this )) );

        ModelASTUtils.addTrigger( result.getModelASTPipelineDef(), modelASTTrigger );  (2)
        return true;
    }
}
```
▼