@Override
                public void disposeTracer(final OperationTracer tracer) {
                  // single-test mode doesn't need to track tracers
                }
Default constructor for the T8nServerSubCommand class. This constructor is required by PicoCLI
and assigns null to parentCommand.
ethereum/evmtool/src/main/java/org/hyperledger/besu/evmtool/T8nServerSubCommand.java