Improve discovering javaSource based on maven.compiler properties, default as 8

We can recognize based on properties:
- maven.compiler.release
- maven.compiler.source
- maven.compiler.target

fix #194

Author: slawekjaranowski

modello-core/src/main/java/org/codehaus/modello/ModelloParameterConstants.java

@@ -51,6 +51,8 @@ public class ModelloParameterConstants {
      */
     public static final String OUTPUT_JAVA_SOURCE = "modello.output.java.source";
 
+    public static final String OUTPUT_JAVA_SOURCE_DEFAULT = "8";
+
     public static final String OUTPUT_XDOC_FILE_NAME = "modello.output.xdoc.file";
 
     public static final String OUTPUT_XSD_FILE_NAME = "modello.output.xsd.file";

modello-maven-plugin/src/main/java/org/codehaus/modello/maven/AbstractModelloSourceGeneratorMojo.java

@@ -23,7 +23,10 @@
  */
 
 import java.io.File;
+import java.util.Optional;
 import java.util.Properties;
+import java.util.function.Supplier;
+import java.util.stream.Stream;
 
 import org.apache.maven.plugins.annotations.Parameter;
 import org.codehaus.modello.ModelloParameterConstants;
@@ -47,10 +50,20 @@ public abstract class AbstractModelloSourceGeneratorMojo extends AbstractModello
     private String encoding;
 
     /**
-     * Generate Java 5 sources, with generic collections.
+     * The java source level used for generating outputs classes.
+     * <p/>
+     * Will be discovered from project properties, in order:
+     * <ul>
+     *     <li><code>maven.compiler.release</code></li>
+     *     <li><code>maven.compiler.source</code></li>
+     *     <li><code>maven.compiler.target</code></li>
+     * </ul>
+     *
+     * If all of above properties was not be set, default value as <b>8</b> will be used.
+     *
      * @since 1.0
      */
-    @Parameter(defaultValue = "${maven.compiler.source}")
+    @Parameter
     private String javaSource;
 
     /**
@@ -85,9 +98,33 @@ protected void customizeParameters(Properties parameters) {
             if (javaSource.startsWith("1.")) {
                 javaSource = javaSource.substring("1.".length());
             }
-            parameters.setProperty(ModelloParameterConstants.OUTPUT_JAVA_SOURCE, javaSource);
+        } else {
+            javaSource = discoverJavaSource();
         }
+        getLog().debug("javaSource=" + javaSource);
+        parameters.setProperty(ModelloParameterConstants.OUTPUT_JAVA_SOURCE, javaSource);
 
         parameters.setProperty(ModelloParameterConstants.DOM_AS_XPP3, Boolean.toString(domAsXpp3));
     }
+
+    private String discoverJavaSource() {
+        Properties projectProperties = getProject().getProperties();
+
+        Supplier<String> release = () -> projectProperties.getProperty("maven.compiler.release");
+        Supplier<String> source = () -> projectProperties.getProperty("maven.compiler.source");
+        Supplier<String> target = () -> projectProperties.getProperty("maven.compiler.target");
+
+        Optional<String> jSource = Stream.of(release, source, target)
+                .map(Supplier::get)
+                .filter(s -> s != null && !s.isEmpty())
+                .findFirst();
+
+        if (jSource.isPresent()) {
+            return jSource.get();
+        } else {
+            getLog().warn("javaSource was not discovered - use default value "
+                    + ModelloParameterConstants.OUTPUT_JAVA_SOURCE_DEFAULT);
+            return ModelloParameterConstants.OUTPUT_JAVA_SOURCE_DEFAULT;
+        }
+    }
 }

modello-maven-plugin/src/test/java/org/codehaus/modello/maven/AbstractModelloSourceGeneratorMojoTest.java

@@ -0,0 +1,78 @@
+package org.codehaus.modello.maven;
+
+import java.util.Properties;
+
+import org.apache.maven.model.Model;
+import org.apache.maven.project.MavenProject;
+import org.codehaus.modello.ModelloParameterConstants;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class AbstractModelloSourceGeneratorMojoTest {
+
+    private class ModelloSourceGeneratorMojoTest extends AbstractModelloSourceGeneratorMojo {
+
+        private final Properties projectProperties;
+
+        ModelloSourceGeneratorMojoTest(Properties projectProperties) {
+            this.projectProperties = projectProperties;
+        }
+
+        @Override
+        protected String getGeneratorType() {
+            return null;
+        }
+
+        @Override
+        public MavenProject getProject() {
+            Model model = new Model();
+            model.setProperties(projectProperties);
+            MavenProject project = new MavenProject();
+            project.setModel(model);
+            return project;
+        }
+    }
+
+    private void executeJavaSourceTest(Properties projectProperties, String expexted) {
+        ModelloSourceGeneratorMojoTest modelloSourceGeneratorMojoTest =
+                new ModelloSourceGeneratorMojoTest(projectProperties);
+        Properties properties = new Properties();
+
+        modelloSourceGeneratorMojoTest.customizeParameters(properties);
+
+        assertEquals(properties.getProperty(ModelloParameterConstants.OUTPUT_JAVA_SOURCE), expexted);
+    }
+
+    @Test
+    public void testJavaSourceDefault() {
+        executeJavaSourceTest(new Properties(), ModelloParameterConstants.OUTPUT_JAVA_SOURCE_DEFAULT);
+    }
+
+    @Test
+    public void testJavaSourceFromRelease() {
+        Properties projectProperties = new Properties();
+        projectProperties.setProperty("maven.compiler.release", "11");
+        projectProperties.setProperty("maven.compiler.source", "xxx");
+        projectProperties.setProperty("maven.compiler.target", "xxx");
+
+        executeJavaSourceTest(projectProperties, "11");
+    }
+
+    @Test
+    public void testJavaSourceFromSource() {
+        Properties projectProperties = new Properties();
+        projectProperties.setProperty("maven.compiler.source", "11");
+        projectProperties.setProperty("maven.compiler.target", "xxx");
+
+        executeJavaSourceTest(projectProperties, "11");
+    }
+
+    @Test
+    public void testJavaSourceFromTarget() {
+        Properties projectProperties = new Properties();
+        projectProperties.setProperty("maven.compiler.target", "11");
+
+        executeJavaSourceTest(projectProperties, "11");
+    }
+}

modello-maven-plugin/src/test/java/org/codehaus/modello/maven/ModelloConvertersMojoTest.java

@@ -25,6 +25,7 @@
 import java.io.File;
 import java.util.Arrays;
 
+import org.apache.maven.project.MavenProject;
 import org.codehaus.modello.core.ModelloCore;
 import org.codehaus.plexus.ContainerConfiguration;
 import org.codehaus.plexus.PlexusTestCase;
@@ -66,6 +67,8 @@ public void testModelloConvertersMojo() throws Exception {
 
         mojo.setBuildContext(buildContext);
 
+        mojo.setProject(new MavenProject());
+
         mojo.execute();
 
         // ----------------------------------------------------------------------

modello-maven-plugin/src/test/java/org/codehaus/modello/maven/ModelloJavaMojoTest.java

@@ -25,6 +25,7 @@
 import java.io.File;
 import java.util.Arrays;
 
+import org.apache.maven.project.MavenProject;
 import org.codehaus.modello.core.ModelloCore;
 import org.codehaus.plexus.ContainerConfiguration;
 import org.codehaus.plexus.PlexusTestCase;
@@ -65,6 +66,7 @@ public void testModelloJavaMojo() throws Exception {
         mojo.setModelloCore(modelloCore);
 
         mojo.setBuildContext(buildContext);
+        mojo.setProject(new MavenProject());
 
         mojo.execute();