FIX #380 Main parameter doesn't support Converter

src/main/java/com/beust/jcommander/JCommander.java

@@ -753,6 +753,13 @@ else if (commands.isEmpty()) {
                     String value = a; // If there's a non-quoted version, prefer that one
                     Object convertedValue = value;
 
+                    // Fix
+                    // Main parameter doesn't support Converter
+                    // https://github.com/cbeust/jcommander/issues/380
+                    if (mainParameter.annotation.converter() != null && mainParameter.annotation.converter() != NoConverter.class){
+                        convertedValue = convertValue(mainParameter.parameterized, mainParameter.parameterized.getType(), null, value);
+                    }
+
                     Type genericType = mainParameter.parameterized.getGenericType();
                     if (genericType instanceof ParameterizedType) {
                         ParameterizedType p = (ParameterizedType) genericType;

src/test/java/com/beust/jcommander/JCommanderTest.java

@@ -1656,6 +1656,18 @@ class Args {
                 .build();
     }
 
+    @Test
+    public void mainWithConverter() {
+
+        String path = "..";
+        File file = new File(path);
+        ArgsMainParameter3 args = new ArgsMainParameter3();
+        JCommander jc = new JCommander(args);
+
+        jc.parse(path);
+        Assert.assertEquals(file.getAbsolutePath(), args.getPath().getAbsolutePath());
+    }
+
     @Test(enabled = false)
     public static void main(String[] args) {
 

src/test/java/com/beust/jcommander/args/ArgsMainParameter3.java

@@ -0,0 +1,44 @@
+/**
+ * Copyright (C) 2010 the original author or authors.
+ * See the notice.md file distributed with this work for additional
+ * information regarding copyright ownership.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.beust.jcommander.args;
+
+import com.beust.jcommander.Parameter;
+import com.beust.jcommander.converters.FileConverter;
+
+import java.io.File;
+
+/**
+ * A class with main parameter that needs a Converter
+ * 
+ * @author juewe
+ */
+public class ArgsMainParameter3  {
+
+  @Parameter(converter = FileConverter.class)
+  public File path;
+
+  public File getPath() {
+    return path;
+  }
+
+  public void setPath(File path) {
+    this.path = path;
+  }
+
+}