Simplify collection expressions

pmd-core/src/main/java/net/sourceforge/pmd/AbstractPropertySource.java

@@ -32,9 +32,7 @@ public abstract class AbstractPropertySource implements PropertySource {
      * @return a copy of the property descriptors.
      */
     protected List<PropertyDescriptor<?>> copyPropertyDescriptors() {
-        List<PropertyDescriptor<?>> copy = new ArrayList<>(propertyDescriptors.size());
-        copy.addAll(propertyDescriptors);
-        return copy;
+        return new ArrayList<>(propertyDescriptors);
     }
 
     /**
@@ -43,10 +41,7 @@ public abstract class AbstractPropertySource implements PropertySource {
      * @return a copy of the values
      */
     protected Map<PropertyDescriptor<?>, Object> copyPropertyValues() {
-        Map<PropertyDescriptor<?>, Object> copy = new HashMap<>(
-                propertyValuesByDescriptor.size());
-        copy.putAll(propertyValuesByDescriptor);
-        return copy;
+        return new HashMap<>(propertyValuesByDescriptor);
     }
 
     /**

pmd-core/src/main/java/net/sourceforge/pmd/SourceCodeProcessor.java

@@ -7,18 +7,22 @@ import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.io.Reader;
 import java.io.UnsupportedEncodingException;
-import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
+import org.apache.commons.io.IOUtils;
+
 import net.sourceforge.pmd.benchmark.Benchmark;
 import net.sourceforge.pmd.benchmark.Benchmarker;
-import net.sourceforge.pmd.lang.*;
+import net.sourceforge.pmd.lang.Language;
+import net.sourceforge.pmd.lang.LanguageVersion;
+import net.sourceforge.pmd.lang.LanguageVersionHandler;
+import net.sourceforge.pmd.lang.Parser;
+import net.sourceforge.pmd.lang.VisitorStarter;
 import net.sourceforge.pmd.lang.ast.Node;
 import net.sourceforge.pmd.lang.ast.ParseException;
 import net.sourceforge.pmd.lang.xpath.Initializer;
 
-import org.apache.commons.io.IOUtils;
-
 public class SourceCodeProcessor {
 
     private final PMDConfiguration configuration;
@@ -141,13 +145,10 @@ public class SourceCodeProcessor {
 		usesDFA(languageVersion, rootNode, ruleSets, language);
 		usesTypeResolution(languageVersion, rootNode, ruleSets,language);
 		
-		List<Node> acus = new ArrayList<>();
-		acus.add(rootNode);
+		List<Node> acus = Collections.singletonList(rootNode);
 		ruleSets.apply(acus, ctx, language);
 	}
 
-
-
 	private void determineLanguage(RuleContext ctx) {
 		// If LanguageVersion of the source file is not known, make a determination
 		if (ctx.getLanguageVersion() == null) {

pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/AbstractRule.java

@@ -68,15 +68,11 @@ public abstract class AbstractRule extends AbstractPropertySource implements Rul
 	}
 
 	private List<String> copyExamples() {
-		List<String> copy = new ArrayList<>(examples.size());
-		copy.addAll(examples);
-		return copy;    	
+		return new ArrayList<>(examples);
 	}
 
 	private List<String> copyRuleChainVisits() {
-		List<String> copy = new ArrayList<>(ruleChainVisits.size());
-		copy.addAll(ruleChainVisits);
-		return copy;
+		return new ArrayList<>(ruleChainVisits);
 	}
 
 	/**