Gets the System.IO.Stream containing the content of this ContentStream object.

It is the caller's responsibility to dispose the returned stream after usage.

Note 1: this method returns null if the current ContentStream object is empty.

Note 2: in StartDoc/EndDoc mode this method is not supported and will throw an exception.

Note 3: In some rare cases a page's content stream can break inside an operator, for example, some operands are in Page.ContentStreams[0] and other operands are in Page.ContentStreams[1]. This is weird but does not contradict the PDF Specification. To avoid such situations use GetStream().