cglib/src/main/java/net/sf/cglib/core/CodeEmitter.java
public void zero_or_null(Type type) {
        if (TypeUtils.isPrimitive(type)) {
            switch (type.getSort()) {
            case Type.DOUBLE:
                push(0d);
                break;
            case Type.LONG:
                push(0L);
                break;
            case Type.FLOAT:
                push(0f);
                break;
            case Type.VOID:
                aconst_null();
            default:
                push(0);
            }
        } else {
            aconst_null();
        }
    }
public void zero_or_null(Type type) {
        if (TypeUtils.isPrimitive(type)) {
            switch (type.getSort()) {
            case Type.DOUBLE:
                push(0d);
                break;
            case Type.LONG:
                push(0L);
                break;
            case Type.FLOAT:
                push(0f);
                break;
            case Type.VOID:
                aconst_null();
            default:
                push(0);
            }
        } else {
            aconst_null();
        }
    }
Pushes a zero onto the stack if the argument is a primitive class, or a null otherwise.