fix some pmd warnings

Author: rbri

src/main/java/org/htmlunit/html/BaseFrameElement.java

@@ -387,26 +387,32 @@ public final void setSrcAttribute(final String attribute) {
      * {@inheritDoc}
      */
     @Override
-    protected void setAttributeNS(final String namespaceURI, final String qualifiedName, String attributeValue,
+    protected void setAttributeNS(final String namespaceURI, final String qualifiedName, final String attributeValue,
             final boolean notifyAttributeChangeListeners, final boolean notifyMutationObserver) {
         final String qualifiedNameLC = org.htmlunit.util.StringUtils.toRootLowerCase(qualifiedName);
+
         if (null != attributeValue && SRC_ATTRIBUTE.equals(qualifiedNameLC)) {
-            attributeValue = attributeValue.trim();
-        }
+            final String attributeValueTrimmed = attributeValue.trim();
 
-        super.setAttributeNS(namespaceURI, qualifiedNameLC, attributeValue, notifyAttributeChangeListeners,
-                notifyMutationObserver);
+            super.setAttributeNS(namespaceURI, qualifiedNameLC, attributeValueTrimmed, notifyAttributeChangeListeners,
+                    notifyMutationObserver);
 
-        // do not use equals() here
-        // see HTMLIFrameElement2Test.documentCreateElement_onLoad_srcAboutBlank()
-        if (SRC_ATTRIBUTE.equals(qualifiedNameLC) && UrlUtils.ABOUT_BLANK != attributeValue) {
-            if (isAttachedToPage()) {
-                loadSrc();
-            }
-            else {
-                loadSrcWhenAddedToPage_ = true;
+            // do not use equals() here
+            // see HTMLIFrameElement2Test.documentCreateElement_onLoad_srcAboutBlank()
+            if (UrlUtils.ABOUT_BLANK != attributeValueTrimmed) {
+                if (isAttachedToPage()) {
+                    loadSrc();
+                }
+                else {
+                    loadSrcWhenAddedToPage_ = true;
+                }
             }
+
+            return;
         }
+
+        super.setAttributeNS(namespaceURI, qualifiedNameLC, attributeValue, notifyAttributeChangeListeners,
+                notifyMutationObserver);
     }
 
     /**

src/main/java/org/htmlunit/html/DomNode.java

@@ -335,12 +335,13 @@ public DomNode getFirstChild() {
      * @param node the node to check
      * @return {@code true} if this node is an ancestor of the specified node
      */
-    public boolean isAncestorOf(DomNode node) {
-        while (node != null) {
-            if (node == this) {
+    public boolean isAncestorOf(final DomNode node) {
+        DomNode parent = node;
+        while (parent != null) {
+            if (parent == this) {
                 return true;
             }
-            node = node.getParentNode();
+            parent = parent.getParentNode();
         }
         return false;
     }

src/main/java/org/htmlunit/util/StringUtils.java

@@ -241,21 +241,21 @@ public static boolean containsIgnoreCase(final String s, final String expected)
      * @param replaceChars a set of characters to replace, may be null.
      * @return modified String, or the input string if no replace was done.
      */
-    public static String replaceChars(final String str, final String searchChars, String replaceChars) {
+    @SuppressWarnings("null")
+    public static String replaceChars(final String str, final String searchChars, final String replaceChars) {
         if (isEmptyOrNull(str) || isEmptyOrNull(searchChars)) {
             return str;
         }
 
-        replaceChars = replaceChars == null ? "" : replaceChars;
-        final int replaceCharsLength = replaceChars.length();
+        final int replaceCharsLength = replaceChars == null ? 0 : replaceChars.length();
         final int strLength = str.length();
 
         StringBuilder buf = null;
         int i = 0;
         for ( ; i < strLength; i++) {
             final char ch = str.charAt(i);
             final int index = searchChars.indexOf(ch);
-            if (index >= 0) {
+            if (index != -1) {
                 buf = new StringBuilder(strLength);
                 buf.append(str, 0, i);
                 if (index < replaceCharsLength) {
@@ -273,7 +273,7 @@ public static String replaceChars(final String str, final String searchChars, St
         for ( ; i < strLength; i++) {
             final char ch = str.charAt(i);
             final int index = searchChars.indexOf(ch);
-            if (index >= 0) {
+            if (index != -1) {
                 if (index < replaceCharsLength) {
                     buf.append(replaceChars.charAt(index));
                 }