returns the index of the first element in ` xs ` that equals ` x ` , or ` -1 ` if ` x ` is not found in ` xs ` . concode_field_sep PlaceHolder placeHolder concode_field_sep List<T> mutatingConcat concode_elem_sep List<T> allReplaced concode_elem_sep List<T> prepend concode_elem_sep boolean nonEmpty concode_elem_sep List<T> replaced concode_elem_sep List<T> concat concode_elem_sep List<T> mutatingConcatDistinct concode_elem_sep List<T> empty concode_elem_sep List<T> concatDistinct concode_elem_sep List<T> flatten concode_elem_sep boolean contains concode_elem_sep boolean contains concode_elem_sep T find concode_elem_sep T find concode_elem_sep List<T> intersection concode_elem_sep List<T> intersection concode_elem_sep List<T> difference concode_elem_sep List<T> difference concode_elem_sep List<T> shuffle concode_elem_sep List<T> append concode_elem_sep T first
int function ( final @ NonNull List < T > arg0 , final @ NonNull T arg1 ) { return ListUtils . indexOf ( arg0 , arg1 , Object :: equals ) ; }