Empty links in Build-Files

[orbiter88]

Hello,
I migrated my Smart-Contract to the polygon-mainnet. Beforehand I tested my smart-contract successfully on the testnet several times. After 'truffle migrate' my Smart-Contract was successfully deployed to the polygon chain. But when it came to the verification process, I needed to specify the contract-addresses of the libraries I use in my Smart-Contract (not the import links in the smart-contract but the addresses to where these libraries were deployed to). So I went to the build-files to check the addresses under "networks" and "links" (as suggested from openzeppelin). But links is empty ("links": {},). So no addresses to specify and no verification of my smart-contract. I don't know what to do now. Can you help?