Grails with Oracle thick OCI driver authenticate to Oracle with wrong user
You should use a url with this format: jdbc:oracle:oci:/@alias where alias is the wallet alias in your tnsnames.ora file.
This option is documented in several places for example here and here. Most documentation is referencing the thin driver but it works the same way with the OCI driver. This post describes the complete process of creating and using a wallet with the OCI driver