I can't create an attribute 1.15

[Elemental]

 

creating a mob

 

public static AttributeModifierMap.MutableAttribute setCustomAttributes() {
        return MobEntity.func_233666_p_()
                .createMutableAttribute(Attributes.ATTACK_SPEED, 12.0D)
                .createMutableAttribute(Attributes.ARMOR,1.0D)
                .createMutableAttribute(Attributes.ATTACK_DAMAGE, 20.0)
                .createMutableAttribute(Attributes.MAX_HEALTH, 10.0D)
                .createMutableAttribute(Attributes.MOVEMENT_SPEED, 0.250D);

it used to work out now it doesn't

porsle .func_233666_p_ () the next line is highlighted in red. createMutableAttribute(Attributes.ATTACK_SPEED, 12.0 D)

and so on

 

[Elemental]

creating a mob

 

public static AttributeModifierMap.MutableAttribute setCustomAttributes() {
        return MobEntity.func_233666_p_()
                .createMutableAttribute(Attributes.ATTACK_SPEED, 12.0D)
                .createMutableAttribute(Attributes.ARMOR,1.0D)
                .createMutableAttribute(Attributes.ATTACK_DAMAGE, 20.0)
                .createMutableAttribute(Attributes.MAX_HEALTH, 10.0D)
                .createMutableAttribute(Attributes.MOVEMENT_SPEED, 0.250D);

it used to work out now it doesn't

porsle .func_233666_p_ () the next line is highlighted in red. createMutableAttribute(Attributes.ATTACK_SPEED, 12.0 D)

and so on