Refactor LanguageMetdata::extensions usages

pmd-core/src/main/java/net/sourceforge/pmd/lang/LanguageModuleBase.java

@@ -8,6 +8,7 @@ import static net.sourceforge.pmd.util.CollectionUtil.setOf;
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
@@ -269,7 +270,7 @@ public abstract class LanguageModuleBase implements Language {
 
         /**
          * Record the {@linkplain Language#getExtensions() extensions}
-         * assigned to the language. Parameters should not start with a period
+         * assigned to the language. Extensions should not start with a period
          * {@code .}.
          *
          * @param e1     First extensions
@@ -283,6 +284,25 @@ public abstract class LanguageModuleBase implements Language {
             return this;
         }
 
+        /**
+         * Record the {@linkplain Language#getExtensions() extensions}
+         * assigned to the language. Extensions should not start with a period
+         * {@code .}. At least one extension must be provided.
+         *
+         * @param extensions the extensions
+         *
+         * @throws NullPointerException If any extension is null
+         * @throws IllegalArgumentException If no extensions are provided
+         */
+        public LanguageMetadata extensions(Collection<String> extensions) {
+            this.extensions = new ArrayList<>(new HashSet<>(extensions));
+            AssertionUtil.requireContainsNoNullValue("extensions", this.extensions);
+            if (this.extensions.isEmpty()) {
+                throw new IllegalArgumentException("At least one extension is required.");
+            }
+            return this;
+        }
+
         /**
          * Add a new version by its name.
          *

pmd-html/src/main/java/net/sourceforge/pmd/lang/html/HtmlLanguageModule.java

@@ -21,7 +21,7 @@ public final class HtmlLanguageModule extends SimpleLanguageModuleBase {
 
     public HtmlLanguageModule() {
         super(LanguageMetadata.withId(TERSE_NAME).name(NAME)
-                              .extensions(EXTENSIONS.get(0), EXTENSIONS.subList(0, EXTENSIONS.size()).toArray(new String[0]))
+                              .extensions(EXTENSIONS)
                               .addVersion("4")
                               .addDefaultVersion("5"),
               new HtmlHandler());

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/EcmascriptLanguageModule.java

@@ -25,7 +25,7 @@ public class EcmascriptLanguageModule extends SimpleLanguageModuleBase {
     public static final List<String> EXTENSIONS = listOf("js");
 
     public EcmascriptLanguageModule() {
-        super(LanguageMetadata.withId(TERSE_NAME).name(NAME).extensions(EXTENSIONS.get(0))
+        super(LanguageMetadata.withId(TERSE_NAME).name(NAME).extensions(EXTENSIONS)
                               .addVersion("3")
                               .addVersion("5")
                               .addVersion("6", "ES6", "ES2015")

pmd-jsp/src/main/java/net/sourceforge/pmd/lang/jsp/JspLanguageModule.java

@@ -23,7 +23,7 @@ public class JspLanguageModule extends SimpleLanguageModuleBase {
 
     public JspLanguageModule() {
         super(LanguageMetadata.withId(TERSE_NAME).name(NAME).shortName("JSP")
-                              .extensions(EXTENSIONS.get(0), EXTENSIONS.toArray(new String[0]))
+                              .extensions(EXTENSIONS)
                               .addVersion("2")
                               .addDefaultVersion("3"),
               new JspHandler());

pmd-kotlin/src/main/java/net/sourceforge/pmd/lang/kotlin/KotlinLanguageModule.java

@@ -32,7 +32,8 @@ public class KotlinLanguageModule extends SimpleLanguageModuleBase {
      * Create a new instance of Kotlin Language Module.
      */
     public KotlinLanguageModule() {
-        super(LanguageMetadata.withId(TERSE_NAME).name(NAME).extensions(EXTENSIONS.get(0), EXTENSIONS.toArray(new String[0]))
+        super(LanguageMetadata.withId(TERSE_NAME).name(NAME)
+                              .extensions(EXTENSIONS)
                               .addVersion("1.6")
                               .addDefaultVersion("1.7"),
               new KotlinHandler());

pmd-modelica/src/main/java/net/sourceforge/pmd/lang/modelica/ModelicaLanguageModule.java

@@ -19,7 +19,7 @@ public class ModelicaLanguageModule extends SimpleLanguageModuleBase {
 
     public ModelicaLanguageModule() {
         super(LanguageMetadata.withId(TERSE_NAME).name(NAME)
-                              .extensions(EXTENSIONS.get(0))
+                              .extensions(EXTENSIONS)
                               .addVersion("3.4")
                               .addDefaultVersion("3.5"),
               new ModelicaHandler());

pmd-plsql/src/main/java/net/sourceforge/pmd/lang/plsql/PLSQLLanguageModule.java

@@ -34,7 +34,7 @@ public class PLSQLLanguageModule extends SimpleLanguageModuleBase {
         super(
             LanguageMetadata.withId(TERSE_NAME)
                             .name(NAME)
-                            .extensions(EXTENSIONS.get(0), EXTENSIONS.toArray(new String[0]))
+                            .extensions(EXTENSIONS)
                             .addVersion("11g")
                             .addVersion("12c_Release_1", "12.1")
                             .addVersion("12c_Release_2", "12.2")

pmd-scala-modules/pmd-scala-common/src/main/java/net/sourceforge/pmd/lang/scala/ScalaLanguageModule.java

@@ -35,7 +35,8 @@ public class ScalaLanguageModule extends SimpleLanguageModuleBase {
      * Create a new instance of Scala Language Module.
      */
     public ScalaLanguageModule() {
-        super(LanguageMetadata.withId(TERSE_NAME).name(NAME).extensions(EXTENSIONS.get(0))
+        super(LanguageMetadata.withId(TERSE_NAME).name(NAME)
+                              .extensions(EXTENSIONS)
                               .addVersion("2.10")
                               .addVersion("2.11")
                               .addVersion("2.12")

pmd-swift/src/main/java/net/sourceforge/pmd/lang/swift/SwiftLanguageModule.java

@@ -29,7 +29,7 @@ public class SwiftLanguageModule extends SimpleLanguageModuleBase {
      */
     public SwiftLanguageModule() {
         super(LanguageMetadata.withId(TERSE_NAME).name(NAME)
-                              .extensions(EXTENSIONS.get(0))
+                              .extensions(EXTENSIONS)
                               .addVersion("4.2")
                               .addVersion("5.0")
                               .addVersion("5.1")

pmd-visualforce/src/main/java/net/sourceforge/pmd/lang/vf/VfLanguageModule.java

@@ -31,9 +31,10 @@ public class VfLanguageModule extends SimpleLanguageModuleBase {
     }
 
     private static LanguageMetadata createMetdata() {
-        LanguageMetadata languageMetadata = LanguageMetadata.withId(TERSE_NAME).name(NAME)
+        LanguageMetadata languageMetadata =
-                .extensions(EXTENSIONS.get(0), EXTENSIONS.toArray(new String[0]))
+                LanguageMetadata.withId(TERSE_NAME).name(NAME)
-                .dependsOnLanguage(ApexLanguageModule.TERSE_NAME);
+                                .extensions(EXTENSIONS)
+                                .dependsOnLanguage(ApexLanguageModule.TERSE_NAME);
         // use the same versions as in Apex
         int lastVersion = ApexLanguageModule.VERSIONS.size() - 1;
         ApexLanguageModule.VERSIONS.subList(0, lastVersion).forEach(languageMetadata::addVersion);

pmd-xml/src/main/java/net/sourceforge/pmd/lang/xml/XmlLanguageModule.java

@@ -23,7 +23,7 @@ public class XmlLanguageModule extends SimpleLanguageModuleBase {
 
     public XmlLanguageModule() {
         super(LanguageMetadata.withId(TERSE_NAME).name(NAME)
-                              .extensions(EXTENSIONS.get(0))
+                              .extensions(EXTENSIONS)
                               .addVersion("1.0")
                               .addDefaultVersion("1.1"),
                 new XmlHandler());