Help for Editing Item Attributes

[Boaphil]

I am trying to edit the Attributes of a Custom Class extending SwordItem.
To do that I am Overriding the getAttributeModifiers Method like this:

@Override
public Multimap<Attribute, AttributeModifier> getAttributeModifiers(EquipmentSlotType slot, ItemStack stack)
    {
    final Multimap<Attribute, AttributeModifier> attributes = super.getAttributeModifiers(slot, stack);

    if(slot == EquipmentSlotType.MAINHAND)
    {
        replaceModifier(attributes, Attributes.ATTACK_SPEED, EnmaItem.ATTACK_SPEED_MODIFIER, 2);
    }

    return attributes;
}

with Extracted Method replaceModifier:

private void replaceModifier(Multimap<Attribute, AttributeModifier> attributes, Attribute attribute, UUID id, double multiplier)
{
    final Collection<AttributeModifier> modifiers = attributes.get(attribute);
    AttributeModifier selectedModifier = null;
    for (AttributeModifier modifier: modifiers)
    {
        if(modifier.getID().equals(id))
        {
            selectedModifier = modifier;
            break;
        }
    }
    
    if(selectedModifier != null)
    {
        modifiers.remove(selectedModifier);
        modifiers.add(new AttributeModifier(
                selectedModifier.getID(),
                selectedModifier.getName(),
                selectedModifier.getAmount() * multiplier,
                selectedModifier.getOperation()));
    }
}

But I get an UnsupportedOpterationException which means that the modifiers.remove() is not supported by my collection.
I just don't know how I can try to edit the Attributes differntly.

Edited April 29, 2022 by Boaphil
Edited typo

[Boaphil]

Alright thanks, creating a new Multimap fixed my issue