The AbstractHttpClientWagon class statically creates both a PoolingHttpClientConnectionManager and a client that uses said connection manager. This is fine, had it not been the case that the client itself is a final field and is never updated.
Thus, using setPoolingHttpClientConnectionManager has no effect as the client is based on the PoolingHttpClientConnectionManager created at startup. This affects users that e.g. may want to change the SSLContext to support self-signed certificates.