Adding ColorSpace to resources causes the stream to close - pdf

Question

I am trying very simple steps to add colorspace to resources using PDFBOX version 2.0.7, but it is not working.
I have PDF "pdf1.pdf", I am reading the colorspaces from this file and adding them to HashMap, then I am creating new resources and trying to add the colorspaces to the newly created resources. But it is not working
So the first Step, I read the colorSpaces from the sourcePdf file and add them to HashMap:
seperationColors = new HashMap<COSName, PDColorSpace>();
PDDocument sourcePdfFile = null;
try {
sourcePdfFile = PDDocument.load(new FileInputStream(new File(pdfPath)));
PDPage page = sourcePdfFile.getPages().get(0);
page.getContents();
for (COSName name : page.getResources().getColorSpaceNames()) {
PDColor color = page.getResources().getColorSpace(name).getInitialColor();
if (color.getColorSpace() instanceof PDSeparation) {
seperationColors.put(name, page.getResources().getColorSpace(name));
}
}
} catch (FileNotFoundException e) {
// e.printStackTrace();
} catch (IOException e) {
// e.printStackTrace();
} finally {
if (sourcePdfFile != null)
try {
sourcePdfFile.close();
} catch (IOException e) {
e.printStackTrace();
} finally {
sourcePdfFile = null;
}
}
}
Then, at later stages in the code, I want to create new PDF document, and add the colorSpaces from the source Pdf to the new one.
PDResources newResources = new PDResources();
PDColorSpace colorSpace = originalDocumentColorSpaces.values().iterator().next();
newResources.add(colorSpace);
newResources will have the error: COSDictionary{COSStream has been closed and cannot be read. Perhaps its enclosing PDDocument has been closed?}
after the add operation (line 3)
colorSpace is of type PDSeperation.
Any clue?