Current implementation of InvokerBytecodeGenerator emits optimized bytecode for small Integer and Long constants, while Byte, Short and Character falls through and is treated as Object.

        if (con instanceof Integer) {
            emitIconstInsn((int) con);
            return;
        }

could reasonably be replaced with:

        if (con instanceof Integer || con instanceof Short || con instanceof Byte || con instanceof Character) {
            emitIconstInsn((int) con);
            return;
        }