Access to flat fields through VarHandles is performed with the code generated in VarHandleValues.java. In this generated code, there's a pattern of testing the value returned by Unsafe.getValue() against null to substitute null with the all-zero default value.

Exemple:

        @ForceInline
        static Object get(VarHandle ob) {
            FieldStaticReadOnly handle = (FieldStaticReadOnly) ob.target();
            Object value = UNSAFE.getValue(handle.base,
                                 handle.fieldOffset, handle.fieldType);
            if (value == null && handle.checkedFieldType instanceof NullRestrictedCheckedType) {
                return ValueClass.zeroInstance(handle.fieldType);
            }
            return value;
        }

 ~~While this is a required practice when accessing reference fields (which include non-flat value fields), this check is useless for flat value fields. Unsafe.getValue() will never return null for a null-free flat field.~~

Note: Now with verifier-enforced null restriction, this check is useless for any read access.