No driverType in Oracle JDBC driver

Database access in WebSphere Application Server is performed through JDBC Providers. JDBC Provider is a configuration element specifying JDBC driver class. For actual database access, one creates Data Sources underneath a JDBC Provider.
At runtime, the first time a data source is accessed, corresponding JDBC Provider is activated. At this time, WebSphere logs a series of informational messages detailing JDBC Provider version and configuration. One of the messages you can see in SystemOut log is DSRA8208I, which Infocenter documents this way:

DSRA8208I: JDBC driver type : {0}
Explanation: The JDBC driver type.
User Response: The JDBC driver type is now used by applications.

Driver type is JDBC driver type and nowadays almost universally equals 4 (pure Java).
When DB2 provider is in use, you might see this:
DSRA8208I: JDBC driver type : 4

However, with Oracle provider the message shows an empty driver type, which may cause confusion or concerns :
DSRA8208I: JDBC driver type : ""

What happened here? Has the driver loaded incorrectly or is unrecognized? Don’t worry. There is no reason for alarm – Oracle provider does not have “driverType” parameter and so this value is always empty with Oracle.