Creating a file under product with Workflow

I want a file to be created in the product when the user starts the workflow process. I prepared a code for this, but I could not proceed further because I received an error in the expression.

How can I perform such an operation in the workflow?

What are the errors in my code?

CODE:

try {
 wt.org.WTPrincipal wtPrincipal = wt.session.SessionHelper.manager.getPrincipal();
 wt.org.WTPrincipalReference principalReference = wt.org.WTPrincipalReference.newWTPrincipalReference(wtPrincipal);

 // Assuming productId is defined somewhere in your code
 wt.folder.Folder productFolder = wt.folder.Folder.newFolder();
 productFolder = wt.pdmlink.PDMLinkProduct(productId);

 wt.folder.Folder newFolder = wt.folder.Folder.create();
 newFolder.setName(name);
 newFolder.setDescription(folderDescription);

 wt.folder.FolderHelper.service.addToFolder(productFolder, newFolder);
 wt.fc.PersistenceHelper.manager.save(newFolder);

 System.out.println("Folder created successfully under the product.");
} catch (Exception e) {
 e.printStackTrace();
} 
wt.inf.container.WTContainerRef containerRef = getContainerRefById(productId);
wt.query.QuerySpec querySpec = new wt.query.QuerySpec(wt.folder.Folder.class);
querySpec.appendSearchCondition(
 new wt.query.SearchCondition(
 wt.folder.Folder.class,
 wt.folder.Folder.CONTAINER_REFERENCE + "." + wt.inf.container.WTContainerRef.KEY + "." + wt.inf.container.WTContainerRef.ID,
 wt.query.SearchCondition.EQUAL,
 containerRef.getId()
 ),
 new int[]{0}
);

wt.fc.QueryResult queryResult = wt.fc.PersistenceHelper.manager.find(querySpec);
queryResult.nextElement();
wt.inf.container.WTContainerRef containerRef = wt.inf.container.WTContainerRef.newWTContainerRef(containerId);

Note: I defined the productId ande containerId value as a string and added Id.

ERROR:

Checking Syntax...
WfExpression_2287132672.java:97: error: cannot find symbol
 wt.folder.Folder productFolder = wt.folder.Folder.newFolder();
 ^
 symbol: method newFolder()
 location: interface Folder
WfExpression_2287132672.java:98: error: cannot find symbol
 productFolder = wt.pdmlink.PDMLinkProduct(productId);
 ^
 symbol: class pdmlink
 location: package wt
WfExpression_2287132672.java:100: error: cannot find symbol
 wt.folder.Folder newFolder = wt.folder.Folder.create();
 ^
 symbol: method create()
 location: interface Folder
WfExpression_2287132672.java:101: error: cannot find symbol
 newFolder.setName(name);
 ^
 symbol: method setName(String)
 location: variable newFolder of type Folder
WfExpression_2287132672.java:102: error: cannot find symbol
 newFolder.setDescription(folderDescription);
 ^
 symbol: variable folderDescription
 location: class WfExpression_2287132672
WfExpression_2287132672.java:104: error: cannot find symbol
 wt.folder.FolderHelper.service.addToFolder(productFolder, newFolder);
 ^
 symbol: method addToFolder(Folder,Folder)
 location: variable service of type FolderService
WfExpression_2287132672.java:111: error: cannot find symbol
wt.inf.container.WTContainerRef containerRef = getContainerRefById(productId);
 ^
 symbol: method getContainerRefById(String)
 location: class WfExpression_2287132672
WfExpression_2287132672.java:116: error: cannot find symbol
 wt.folder.Folder.CONTAINER_REFERENCE + "." + wt.inf.container.WTContainerRef.KEY + "." + wt.inf.container.WTCon
Syntax check complete.