It might be required for you to import the package if you encounter any issues (like casting an Array), so better be safe than sorry and add the import.
import crafttweaker.entity.Attribute;

ZenGetter	GetterMethod	Return Type
ZenGetter nome	GetterMethod getName()	Return Type string
ZenGetter defaultValue	GetterMethod getDefaultValue()	Return Type double
ZenGetter shouldWatch	GetterMethod getShouldWatch()	Return Type boolean
ZenGetter parent	GetterMethod getParent()	Return Type IEntityAttribute

• double clampValue(double Value) → Does something...