1. A method, comprising: discovering, by a processor, one or more instances of external resource access by statically analyzing application code; specifying, by the processor, addresses of the discovered instances of external resource access; identifying, by the processor, one or more addresses of one or more constants in the application code and a configuration repository of the specified addresses of discovered instances of external resource access, the one or more constants being stored in a non-transitory computer readable storage medium; updating, by the processor, one or more values of the one or more constants in the application code and the configuration repository; wherein the application code is updated by replacing at least one of the one or more values of the one or more constants with one or more updated values of the one or more constants; and wherein the updating includes matching one or more addresses of the external resources with a table mapping the one or more addresses of the one or more constants to one or more updated constant addresses; and using, by the processor, the one or more updated values of the one or more constants in the application code and the configuration repository in current or future migrations.