Revert 0a2debb commit changes in AbstractRenderer, fix issue in a more appropriate way, minor fixes for the sake of .net porting

Author: yulian-gaponenko

layout/src/main/java/com/itextpdf/layout/renderer/AbstractRenderer.java

@@ -294,19 +294,7 @@ public PdfFont getPropertyAsFont(int property) {
      * @return a {@link Color}
      */
     public Color getPropertyAsColor(int property) {
-        Object object = getProperty(property);
-
-        if(object == null) {
-            return null;
-        }
-
-        if(object instanceof Color) {
-            return (Color) object;
-        } else if (object instanceof Background) {
-            return ((Background)object).getColor();
-        }
-
-        throw new IllegalStateException("The type of property is unexpected.. property: " + property + ", class: " + object.getClass());
+        return this.<Color>getProperty(property);
     }
 
     /**

layout/src/main/java/com/itextpdf/layout/renderer/AccessibleAttributesApplier.java

@@ -56,6 +56,7 @@ This file is part of the iText (R) project.
 import com.itextpdf.kernel.pdf.tagging.PdfStructElem;
 import com.itextpdf.kernel.pdf.tagutils.AccessibilityProperties;
 import com.itextpdf.kernel.pdf.tagutils.IAccessibleElement;
+import com.itextpdf.layout.property.Background;
 import com.itextpdf.layout.property.HorizontalAlignment;
 import com.itextpdf.layout.property.ListNumberingType;
 import com.itextpdf.layout.property.Property;
@@ -154,9 +155,9 @@ public static void applyTableAttributes(AbstractRenderer renderer) {
     }
 
     private static void applyCommonLayoutAttributes(AbstractRenderer renderer, PdfDictionary attributes) {
-        Color backgroundColor = renderer.getPropertyAsColor(Property.BACKGROUND);
-        if (backgroundColor != null && backgroundColor instanceof DeviceRgb) {
-            attributes.put(PdfName.BackgroundColor, new PdfArray(backgroundColor.getColorValue()));
+        Background background = renderer.<Background>getProperty(Property.BACKGROUND);
+        if (background != null && background.getColor() instanceof DeviceRgb) {
+            attributes.put(PdfName.BackgroundColor, new PdfArray(background.getColor().getColorValue()));
         }
 
         //TODO NOTE: applying border attributes for cells is temporarily turned off on purpose. Remove this 'if' in future.

layout/src/test/java/com/itextpdf/layout/BackgroundColorTest.java

@@ -37,9 +37,6 @@ public static void beforeClass() {
         createDestinationFolder(destinationFolder);
     }
 
-    @Rule
-    public ExpectedException thrown = ExpectedException.none();
-
     @Test
     public void shouldAddBackgroundColorAttributeToAccessiblityWhenBackgroundColorIsSet() throws IOException, XMPException, InterruptedException {
         fileName = "simpleBackgroundColorTest.pdf";