[MPH-193] Document charset for evaluate goal file output

This closes #123

src/main/java/org/apache/maven/plugins/help/AbstractEffectiveMojo.java

@@ -25,14 +25,14 @@
 import java.io.StringReader;
 import java.io.StringWriter;
 import java.io.Writer;
+import java.nio.file.Files;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Properties;
 import java.util.Set;
 
-import org.codehaus.plexus.util.WriterFactory;
 import org.codehaus.plexus.util.xml.XMLWriter;
 import org.codehaus.plexus.util.xml.XmlWriterUtil;
 import org.jdom2.Document;
@@ -49,7 +49,7 @@
  */
 public abstract class AbstractEffectiveMojo extends AbstractHelpMojo {
     /**
-     * Utility method to write an XML content in a given file.
+     * Utility method to write an XML content to a given file.
      *
      * @param output is the wanted output file.
      * @param content contains the XML content to be written to the file.
@@ -62,7 +62,7 @@ protected static void writeXmlFile(File output, String content) throws IOExcepti
         }
 
         output.getParentFile().mkdirs();
-        try (Writer out = WriterFactory.newXmlWriter(output)) {
+        try (Writer out = Files.newBufferedWriter(output.toPath())) {
             out.write(content);
         }
     }

src/main/java/org/apache/maven/plugins/help/AbstractHelpMojo.java

@@ -21,6 +21,7 @@
 import java.io.File;
 import java.io.IOException;
 import java.io.Writer;
+import java.nio.file.Files;
 
 import org.apache.maven.artifact.Artifact;
 import org.apache.maven.execution.MavenSession;
@@ -33,7 +34,6 @@
 import org.apache.maven.project.MavenProject;
 import org.apache.maven.project.ProjectBuilder;
 import org.apache.maven.project.ProjectBuildingRequest;
-import org.codehaus.plexus.util.WriterFactory;
 import org.eclipse.aether.RepositoryException;
 import org.eclipse.aether.RepositorySystem;
 import org.eclipse.aether.RepositorySystemSession;
@@ -81,15 +81,16 @@ public abstract class AbstractHelpMojo extends AbstractMojo {
     protected MavenSession session;
 
     /**
-     * Optional parameter to write the output of this help in a given file, instead of writing to the console.
+     * Optional parameter to write the output of this help to a given file using UTF-8 encoding,
+     * instead of writing to the console.
      * <br>
      * <b>Note</b>: Could be a relative path.
      */
     @Parameter(property = "output")
     protected File output;
 
     /**
-     * Utility method to write a content in a given file.
+     * Utility method to write a content to a given file.
      *
      * @param output is the wanted output file.
      * @param content contains the content to be written to the file.
@@ -101,7 +102,7 @@ protected static void writeFile(File output, StringBuilder content) throws IOExc
     }
 
     /**
-     * Utility method to write a content in a given file.
+     * Utility method to write a content to a given file.
      *
      * @param output is the wanted output file.
      * @param content contains the content to be written to the file.
@@ -113,7 +114,7 @@ protected static void writeFile(File output, String content) throws IOException
         }
 
         output.getParentFile().mkdirs();
-        try (Writer out = WriterFactory.newPlatformWriter(output)) {
+        try (Writer out = Files.newBufferedWriter(output.toPath())) {
             out.write(content);
         }
     }

src/main/java/org/apache/maven/plugins/help/DescribeMojo.java

@@ -240,7 +240,7 @@ public void execute() throws MojoExecutionException, MojoFailureException {
     // ----------------------------------------------------------------------
 
     /**
-     * Method to write the Mojo description into the output file
+     * Method to write the Mojo description to the output file
      *
      * @param descriptionBuffer contains the description to be written to the file
      * @throws MojoExecutionException if any