fix some pmd warnings

Author: rbri

src/main/java/org/htmlunit/DefaultPageCreator.java

@@ -119,8 +119,7 @@ public static PageType determinePageType(final String contentType) {
             return PageType.UNKNOWN;
         }
 
-        final String contentTypeLC = org.htmlunit.util.StringUtils
-                                            .toRootLowerCase(contentType);
+        final String contentTypeLC = StringUtils.toRootLowerCase(contentType);
 
         if (MimeType.isJavascriptMimeType(contentTypeLC)) {
             return PageType.JAVASCRIPT;

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

@@ -80,7 +80,7 @@ protected boolean doClickStateUpdate(final boolean shiftKey, final boolean ctrlK
         final String href = getHrefAttribute().trim();
         if (!href.isEmpty()) {
             final HtmlPage page = (HtmlPage) getPage();
-            if (org.htmlunit.util.StringUtils.startsWithIgnoreCase(href, JavaScriptURLConnection.JAVASCRIPT_PREFIX)) {
+            if (StringUtils.startsWithIgnoreCase(href, JavaScriptURLConnection.JAVASCRIPT_PREFIX)) {
                 page.executeJavaScript(
                     href, "javascript url", getStartLineNumber());
                 return false;
@@ -267,7 +267,7 @@ public boolean isDisplayed() {
 
     private Rectangle2D parseRect() {
         // browsers seem to support comma and blank
-        final String[] coords = org.htmlunit.util.StringUtils.splitAtCommaOrBlank(getCoordsAttribute());
+        final String[] coords = StringUtils.splitAtCommaOrBlank(getCoordsAttribute());
 
         double leftX = 0;
         double topY = 0;
@@ -299,7 +299,7 @@ private Rectangle2D parseRect() {
 
     private Circle2D parseCircle() {
         // browsers seem to support comma and blank
-        final String[] coords = org.htmlunit.util.StringUtils.splitAtCommaOrBlank(getCoordsAttribute());
+        final String[] coords = StringUtils.splitAtCommaOrBlank(getCoordsAttribute());
 
         double centerX = 0;
         double centerY = 0;
@@ -328,7 +328,7 @@ private Circle2D parseCircle() {
 
     private Shape2D parsePoly() {
         // browsers seem to support comma and blank
-        final String[] coords = org.htmlunit.util.StringUtils.splitAtCommaOrBlank(getCoordsAttribute());
+        final String[] coords = StringUtils.splitAtCommaOrBlank(getCoordsAttribute());
 
         try {
             if (coords.length > 1) {

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

@@ -1262,7 +1262,7 @@ public void setHidden(final String hidden) {
             return;
         }
 
-        if (org.htmlunit.util.StringUtils.isEmptyString(hidden)) {
+        if (StringUtils.isEmptyString(hidden)) {
             removeAttribute(ATTRIBUTE_HIDDEN);
             return;
         }

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

@@ -77,7 +77,7 @@ public final String getSrcAttribute() {
      */
     public String getSrc() {
         final String src = getSrcAttribute();
-        if (org.htmlunit.util.StringUtils.isEmptyString(src)) {
+        if (StringUtils.isEmptyString(src)) {
             return src;
         }
         try {

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

@@ -87,7 +87,7 @@ public boolean isValid() {
      */
     @Override
     public boolean isCustomErrorValidityState() {
-        return !org.htmlunit.util.StringUtils.isEmptyOrNull(customValidity_);
+        return !StringUtils.isEmptyOrNull(customValidity_);
     }
 
     @Override

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

@@ -297,7 +297,7 @@ public static boolean isJavaScript(String typeAttribute, final String languageAt
         }
 
         if (!StringUtils.isEmptyOrNull(languageAttribute)) {
-            return org.htmlunit.util.StringUtils.startsWithIgnoreCase(languageAttribute, "javascript");
+            return StringUtils.startsWithIgnoreCase(languageAttribute, "javascript");
         }
         return true;
     }

src/main/java/org/htmlunit/javascript/host/Navigator.java

@@ -111,7 +111,7 @@ public Scriptable getLanguages() {
         }
 
         final ArrayList<String> res = new ArrayList<>();
-        final String[] parts = org.htmlunit.util.StringUtils.splitAtComma(acceptLang);
+        final String[] parts = StringUtils.splitAtComma(acceptLang);
         for (final String part : parts) {
             if (!StringUtils.isEmptyOrNull(part)) {
                 final String lang = org.apache.commons.lang3.StringUtils.substringBefore(part, ";").trim();