Fix minor static analysis warnings

Author: jfree

src/main/java/org/jfree/svg/ImageElement.java

@@ -92,7 +92,7 @@ public String toString() {
         StringBuilder sb = new StringBuilder();
         sb.append("ImageElement[");
         sb.append(this.href).append(", ").append(this.image);
-        sb.append("]");
+        sb.append(']');
         return sb.toString();
     }
 

src/main/java/org/jfree/svg/SVGGraphicsDevice.java

@@ -51,6 +51,7 @@ public class SVGGraphicsDevice extends GraphicsDevice {
      * @param defaultConfig  the default configuration.
      */
     public SVGGraphicsDevice(String id, GraphicsConfiguration defaultConfig) {
+        super();
         this.id = id;
         this.defaultConfig = defaultConfig;
     }

src/test/java/org/jfree/svg/TestSVGGraphics2D.java

@@ -926,7 +926,9 @@ void checkClipAfterCreate() {
 
     @Test
     void checkGradientPaintRefGeneration() {
-        if (!(this.g2 instanceof SVGGraphics2D)) return;
+        if (!(this.g2 instanceof SVGGraphics2D)) {
+            return;
+        }
         SVGGraphics2D svg2 = (SVGGraphics2D) this.g2;
         GradientPaint gp0 = new GradientPaint(1.0f, 2.0f, Color.RED, 3.0f, 4.0f, Color.BLUE);
         svg2.setPaint(gp0);