My
@Contract(pure = true)i 
boolean contains(
    Object o
)
throws IOException

From interface:

java.util.Collection
Returns true if this collection contains the specified element. More formally, returns true if and only if this collection contains at least one element e such that (o==null ? e==null : o.equals(e)).

Overrides:

contains in interface Collection
contains in interface I

Params:

o – element whose presence in this collection is to be tested

Returns:

true if this collection contains the specified element

Throws:

NullPointerException – before if the specified element is null and this collection does not permit null elements (optional) after

IOException