EA2 ships with 126.96.36.199 driver, and you have an 188.8.131.52 client.
Either disable the OCI in the preferences, or update your client to 184.108.40.206
The issue is that if you are using the OCI (thick) JDBC driver the version of the JDBC library (in SQLDeveloper) must match the version in your ORACLE_HOME.
It seems SQLDeveloper 4 ships with 220.127.116.11 version of JDBC and you have 18.104.22.168 client installed.
1 Don't use the OCI driver. You can untick the box in Tools |Preferences|Database |Advanced, but some connection types use it anyway.
2 Upgrade your Oracle client.