Currently those two dependencies are defined messy. First they are defined in myfaces-core-project as optional which makes no sence since this project is just the super-project for api and impl and optional dependencies are not transitive. So this has to be removed here.
Furthermore the definitions of validation-api and el-api in the pom of myfaces-api are not completely correct. They should have a scope of compile (default) and should have set optional to true instead of just provided or provided+optional (which is by the way not allowed).
After this issue has been resolved el-api 2.2 will be available on the whole myfaces-api project, however keep in mind that you are only allowed to use the new methods (like getValueReference()) if you checked if the el-api 2.2 is really available first (via ExternalSpecifications). Otherwise you will end up in ClassNotFoundExceptions at runtime when el-api 2.2 is not available in the target system.