Let $f : \mathbb { R } \rightarrow \mathbb { R }$ be a function defined by $f ( x ) = \left\{ \begin{array} { l l } { [ x ] , } & x \leq 2 \\ 0 , & x > 2 \end{array} \right.$,
where $[ x ]$ is the greatest integer less than or equal to $x$. If $I = \int _ { - 1 } ^ { 2 } \frac { x f \left( x ^ { 2 } \right) } { 2 + f ( x + 1 ) } d x$, then the value of $( 4 I - 1 )$ is