When openjpa.Log is set to slf4j, OpenJPA
will delegate to SLF4J API for logging, which provides several adapters or
a simple logging mechanism. For further details on logging adapters and
configuring SLF4J, please see the
SLF4J website.
Note, as SLF4J does not provide a FATAL log level the
SLF4JLogFactory will map it to the ERROR
log level.