Enable "error prone" library that does static code analysis during code compilation

.mvn/jvm.config

@@ -0,0 +1,10 @@
+--add-exports jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.model=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.processing=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED
+--add-opens jdk.compiler/com.sun.tools.javac.code=ALL-UNNAMED
+--add-opens jdk.compiler/com.sun.tools.javac.comp=ALL-UNNAMED

.run/test.run.xml

@@ -1,32 +1,16 @@
 <component name="ProjectRunConfigurationManager">
-  <configuration default="false" name="test" type="MavenRunConfiguration" factoryName="Maven">
-    <MavenSettings>
-      <option name="myGeneralSettings" />
-      <option name="myRunnerSettings" />
-      <option name="myRunnerParameters">
-        <MavenRunnerParameters>
-          <option name="cmdOptions" />
-          <option name="profiles">
-            <set />
-          </option>
-          <option name="goals">
-            <list>
-              <option value="test" />
-            </list>
-          </option>
-          <option name="multimoduleDir" />
-          <option name="pomFileName" />
-          <option name="profilesMap">
-            <map />
-          </option>
-          <option name="projectsCmdOptionValues">
-            <list />
-          </option>
-          <option name="resolveToWorkspace" value="false" />
-          <option name="workingDirPath" value="$PROJECT_DIR$" />
-        </MavenRunnerParameters>
-      </option>
-    </MavenSettings>
-    <method v="2" />
+  <configuration default="false" name="test" type="JUnit" factoryName="JUnit">
+    <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="true" />
+    <option name="ALTERNATIVE_JRE_PATH" value="17" />
+    <option name="PACKAGE_NAME" value="org.xhtmlrenderer" />
+    <option name="MAIN_CLASS_NAME" value="" />
+    <option name="METHOD_NAME" value="" />
+    <option name="TEST_OBJECT" value="package" />
+    <option name="TEST_SEARCH_SCOPE">
+      <value defaultName="wholeProject" />
+    </option>
+    <method v="2">
+      <option name="Make" enabled="true" />
+    </method>
   </configuration>
 </component>

flying-saucer-core/pom.xml

@@ -71,14 +71,6 @@
           </instructions>
         </configuration>
       </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-compiler-plugin</artifactId>
-        <configuration>
-          <source>${java.version}</source>
-          <target>${java.version}</target>
-        </configuration>
-      </plugin>
     </plugins>
   </build>
 </project>

flying-saucer-core/src/main/java/org/xhtmlrenderer/context/ContentFunctionFactory.java

@@ -19,7 +19,8 @@
  */
 package org.xhtmlrenderer.context;
 
-import org.w3c.dom.css.CSSPrimitiveValue;
+import com.google.errorprone.annotations.CheckReturnValue;
+import org.jspecify.annotations.Nullable;
 import org.xhtmlrenderer.css.constants.IdentValue;
 import org.xhtmlrenderer.css.extend.ContentFunction;
 import org.xhtmlrenderer.css.parser.FSFunction;
@@ -35,6 +36,10 @@
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Objects;
+
+import static org.w3c.dom.css.CSSPrimitiveValue.CSS_IDENT;
+import static org.w3c.dom.css.CSSPrimitiveValue.CSS_STRING;
 
 public class ContentFunctionFactory {
     private final List<ContentFunction> _functions = new ArrayList<>();
@@ -46,6 +51,7 @@ public ContentFunctionFactory() {
         _functions.add(new LeaderFunction());
     }
 
+    @Nullable
     public ContentFunction lookupFunction(LayoutContext c, FSFunction function) {
         for (ContentFunction f : _functions) {
             if (f.canHandle(c, function)) {
@@ -65,6 +71,7 @@ public boolean isStatic() {
             return false;
         }
 
+        @Nullable
         @Override
         public String calculate(LayoutContext c, FSFunction function) {
             return null;
@@ -95,14 +102,14 @@ protected boolean isCounter(FSFunction function, String counterName) {
                 List<PropertyValue> parameters = function.getParameters();
                 if (parameters.size() == 1 || parameters.size() == 2) {
                     PropertyValue param = parameters.get(0);
-                    if (param.getPrimitiveType() != CSSPrimitiveValue.CSS_IDENT ||
-                            ! param.getStringValue().equals(counterName)) {
+                    if (param.getPrimitiveType() != CSS_IDENT ||
+                            !Objects.equals(param.getStringValue(), counterName)) {
                         return false;
                     }
 
                     if (parameters.size() == 2) {
                         param = parameters.get(1);
-                        return param.getPrimitiveType() == CSSPrimitiveValue.CSS_IDENT;
+                        return param.getPrimitiveType() == CSS_IDENT;
                     }
 
                     return true;
@@ -163,6 +170,7 @@ public String calculate(RenderingContext c, FSFunction function, InlineText text
             return "";
         }
 
+        @Nullable
         @Override
         public String calculate(LayoutContext c, FSFunction function) {
             return null;
@@ -181,14 +189,14 @@ public boolean canHandle(LayoutContext c, FSFunction function) {
                     FSFunction f = parameters.get(0).getFunction();
                     if (f == null ||
                             f.getParameters().size() != 1 ||
-                            f.getParameters().get(0).getPrimitiveType() != CSSPrimitiveValue.CSS_IDENT ||
-                            ! f.getParameters().get(0).getStringValue().equals("href")) {
+                            f.getParameters().get(0).getPrimitiveType() != CSS_IDENT ||
+                            ! "href".equals(f.getParameters().get(0).getStringValue())) {
                         return false;
                     }
 
                     PropertyValue param = parameters.get(1);
-                    return param.getPrimitiveType() == CSSPrimitiveValue.CSS_IDENT &&
-                            param.getStringValue().equals("page");
+                    return param.getPrimitiveType() == CSS_IDENT &&
+                            Objects.equals(param.getStringValue(), "page");
                 }
             }
 
@@ -253,10 +261,12 @@ public String calculate(RenderingContext c, FSFunction function, InlineText text
             return leaderString;
         }
 
+        @Nullable
+        @CheckReturnValue
         private String getLeaderValue(FSFunction function) {
             final PropertyValue param = function.getParameters().get(0);
             final String value = param.getStringValue();
-            if (param.getPrimitiveType() == CSSPrimitiveValue.CSS_IDENT) {
+            if (param.getPrimitiveType() == CSS_IDENT) {
                 return switch (value) {
                     case "dotted" -> ". ";
                     case "solid" -> "_";
@@ -267,27 +277,30 @@ private String getLeaderValue(FSFunction function) {
             return value;
         }
 
+        @Nullable
         @Override
         public String calculate(LayoutContext c, FSFunction function) {
             return null;
         }
 
         @Override
+        @CheckReturnValue
         public String getLayoutReplacementText() {
             return " . ";
         }
 
         @Override
+        @CheckReturnValue
         public boolean canHandle(LayoutContext c, FSFunction function) {
             if (c.isPrint() && function.is("leader")) {
                 List<PropertyValue> parameters = function.getParameters();
                 if (parameters.size() == 1) {
                     PropertyValue param = parameters.get(0);
-                    return param.getPrimitiveType() == CSSPrimitiveValue.CSS_STRING ||
-                            (param.getPrimitiveType() == CSSPrimitiveValue.CSS_IDENT &&
-                                    (param.getStringValue().equals("dotted") ||
-                                            param.getStringValue().equals("solid") ||
-                                            param.getStringValue().equals("space")));
+                    return param.getPrimitiveType() == CSS_STRING ||
+                            (param.getPrimitiveType() == CSS_IDENT &&
+                                    ("dotted".equals(param.getStringValue()) ||
+                                            "solid".equals(param.getStringValue()) ||
+                                            "space".equals(param.getStringValue())));
                 }
             }
 

flying-saucer-core/src/main/java/org/xhtmlrenderer/context/StyleReference.java

@@ -54,14 +54,17 @@
  * @author Torbjoern Gannholm
  */
 public class StyleReference {
+    @Nullable
     private NamespaceHandler _nsh;
+    @Nullable
     private Document _doc;
     private final StylesheetFactoryImpl _stylesheetFactory;
 
     /**
      * Instance of our element-styles matching class. Will be null if new rules
      * have been added since last match.
      */
+    @Nullable
     private Matcher _matcher;
 
     private UserAgentCallback _uac;

flying-saucer-core/src/main/java/org/xhtmlrenderer/context/StylesheetCache.java

@@ -3,6 +3,7 @@
 import org.xhtmlrenderer.css.sheet.Stylesheet;
 
 import java.util.LinkedHashMap;
+import java.util.Map;
 
 class StylesheetCache extends LinkedHashMap<String, Stylesheet> {
     private static final int cacheCapacity = 16;
@@ -11,7 +12,8 @@ class StylesheetCache extends LinkedHashMap<String, Stylesheet> {
         super(cacheCapacity,  0.75f, true);
     }
 
-    protected boolean removeEldestEntry(java.util.Map.Entry<String, Stylesheet> eldest) {
+    @Override
+    protected boolean removeEldestEntry(Map.Entry<String, Stylesheet> eldest) {
         return size() > cacheCapacity;
     }
 }

flying-saucer-core/src/main/java/org/xhtmlrenderer/context/StylesheetFactoryImpl.java

@@ -30,7 +30,6 @@
 import org.xhtmlrenderer.extend.UserAgentCallback;
 import org.xhtmlrenderer.resource.CSSResource;
 import org.xhtmlrenderer.util.Configuration;
-import org.xhtmlrenderer.util.IOUtil;
 import org.xhtmlrenderer.util.XRLog;
 import org.xml.sax.InputSource;
 
@@ -39,7 +38,6 @@
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.io.Reader;
-import java.io.UnsupportedEncodingException;
 import java.util.Map;
 import java.util.logging.Level;
 
@@ -70,10 +68,12 @@ public StylesheetFactoryImpl(UserAgentCallback userAgentCallback) {
         _cssParser = new CSSParser((uri, message) -> XRLog.cssParse(Level.WARNING, "(" + uri + ") " + message));
     }
 
+    @Override
     public Stylesheet parse(Reader reader, StylesheetInfo info) {
         return parse(reader, info.getUri(), info.getOrigin());
     }
 
+    @Override
     public Stylesheet parse(Reader reader, String uri, Origin origin) {
         try {
             return _cssParser.parseStylesheet(uri, origin, reader);
@@ -96,19 +96,16 @@ private Stylesheet parse(StylesheetInfo info) {
         // since the null resource stream is wrapped in a BufferedInputStream
         InputSource inputSource=cr.getResourceInputSource();
         if (inputSource==null) return null;
-        InputStream is = inputSource.getByteStream();
-        if (is==null) return null;
-        try {
+        try (InputStream is = inputSource.getByteStream()) {
+            if (is == null) return null;
             String charset = Configuration.valueFor("xr.stylesheets.charset-name", "UTF-8");
             return parse(new InputStreamReader(is, charset), info);
-        } catch (UnsupportedEncodingException e) {
-            // Shouldn't happen
+        } catch (IOException e) {
             throw new RuntimeException(e.getMessage(), e);
-        } finally {
-            IOUtil.close(is);
         }
     }
 
+    @Override
     public Ruleset parseStyleDeclaration(Origin origin, String styleDeclaration) {
         return _cssParser.parseDeclaration(origin, styleDeclaration);
     }
@@ -158,6 +155,7 @@ void flushCachedStylesheets() {
     //TODO: this looks a bit odd
     @Nullable
     @CheckReturnValue
+    @Override
     public Stylesheet getStylesheet(StylesheetInfo info) {
         XRLog.load("Requesting stylesheet: " + info.getUri());
 

flying-saucer-core/src/main/java/org/xhtmlrenderer/css/constants/CSSName.java

@@ -1681,6 +1681,7 @@ private CSSName(
      *
      * @return a string representation of the object.
      */
+    @Override
     public String toString() {
         return this.propName;
     }
@@ -1827,14 +1828,15 @@ public int compareTo(CSSName object) {
     }
 
     // FIXME equals, hashcode
-
+    @Override
     public boolean equals(Object o) {
         if (this == o) return true;
         if (!(o instanceof CSSName cssName)) return false;
 
         return FS_ID == cssName.FS_ID;
     }
 
+    @Override
     public int hashCode() {
         return FS_ID;
     }

flying-saucer-core/src/main/java/org/xhtmlrenderer/css/constants/IdentValue.java

@@ -229,6 +229,7 @@ private IdentValue(String ident) {
      *
      * @return a string representation of the object.
      */
+    @Override
     public String toString() {
         return ident;
     }

flying-saucer-core/src/main/java/org/xhtmlrenderer/css/constants/MarginBoxName.java

@@ -68,6 +68,7 @@ private static MarginBoxName addValue(String ident, IdentValue textAlign, IdentV
         return val;
     }
 
+    @Override
     public String toString() {
         return _ident;
     }
@@ -76,10 +77,12 @@ public static MarginBoxName valueOf(String ident) {
         return ALL.get(ident);
     }
 
+    @Override
     public int hashCode() {
         return FS_ID;
     }
 
+    @Override
     public boolean equals(Object o) {
         if (!(o instanceof MarginBoxName)) {
             return false;

flying-saucer-core/src/main/java/org/xhtmlrenderer/css/constants/PageElementPosition.java

@@ -49,6 +49,7 @@ public static PageElementPosition byIdent(String ident) {
         this._ident = ident;
     }
 
+    @Override
     public String toString() {
         return _ident;
     }

flying-saucer-core/src/main/java/org/xhtmlrenderer/css/extend/TreeResolver.java

@@ -22,11 +22,11 @@
 import org.w3c.dom.Node;
 
 /**
+ * Gives the css matcher access to the information it needs about the tree structure.
+ * <p>
+ * Elements are the "things" in the tree structure that can be matched by the matcher.
+ *
  * @author scott
- *         <p>
- *         Gives the css matcher access to the information it needs about the tree structure.
- *         <p>
- *         Elements are the "things" in the tree structure that can be matched by the matcher.
  */
 public interface TreeResolver {
     // XXX Where should this go (used by parser, TreeResolver, and AttributeResolver