presto-main/src/main/java/io/prestosql/metadata/SpecializedFunctionKey.java/SpecializedFunctionKey/equals
class SpecializedFunctionKey:    @Override
    public boolean equals(Object o)
    {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }

        SpecializedFunctionKey that = (SpecializedFunctionKey) o;

        return Objects.equals(boundVariables, that.boundVariables) &&
                Objects.equals(function.getFunctionMetadata().getFunctionId(), that.function.getFunctionMetadata().getFunctionId()) &&
                arity == that.arity;
    }