How to change the color of a circle annotation?

Please take a look at the CircleAnnotation example. It creates a circle annotation with a blue border and red as the interior color:

Colored circle annotation

The code to add this annotation in iText 7 looks like this:

protected void manipulatePdf(String src, String dest) throws Exception {
    PdfDocument pdfDoc = new PdfDocument(new PdfReader(new FileInputStream(src)),
            new PdfWriter(new FileOutputStream(dest)));
    Rectangle rect = new Rectangle(150, 770, 50, 50);

    PdfAnnotation annotation = new PdfCircleAnnotation(rect)
            .setContents("Circle")
            .setTitle(new PdfString("Circle"))
            .setColor(Color.BLUE)
            .setFlags(PdfAnnotation.PRINT)
            .setBorderStyle(PdfAnnotation.STYLE_DASHED)
            .setDashPattern(new PdfArray(new int[]{3, 2}))
            .setBorder(new PdfArray(new float[]{0, 0, 2}))
            .put(PdfName.IC, new PdfArray(new int[]{1, 0, 0}));
    pdfDoc.getFirstPage().addAnnotation(annotation);
    pdfDoc.close();
}

This line sets the interior color:

annotation.put(PdfName.IC, new PdfArray(new int[]{1, 0, 0}));

Caveat:

some PDF viewers (such as Chrome PDF viewer) are not full PDF viewers. They don't support every type of annotation. For instance, if you open hello_circle.pdf in Chrome, you won't see the annotation. That is not a problem caused by the PDF (nor iTextSharp), that is a viewer problem.

Click How to change the color of a circle annotation? if you want to see how to answer this question in iText 5.