Why does Maven warn me about encoding?

Question

My goal is to create an archetype from a project.

When I run a goal that does not involve the maven-archetype-plugin, I can't see any warning:

[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ maven-archetype-base ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Copying 1 resource
[INFO] 
[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ maven-archetype-base ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Copying 0 resource
[INFO]

On the other end, when I run archetype:create-from-project, I get a couple:

[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ maven-archetype-base-archetype ---
[WARNING] Using platform encoding (Cp1252 actually) to copy filtered resources, i.e. build is platform dependent!
[INFO] Copying 10 resources
[INFO] 
[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ maven-archetype-base-archetype ---
[WARNING] Using platform encoding (Cp1252 actually) to copy filtered resources, i.e. build is platform dependent!
[INFO] Copying 2 resources

I know that the "standard" maven way is to use the project.build.sourceEncoding property. I tried adding some more properties to the pom in order to address this issue but none of them worked.

Any ideas? Thanks.

I have the following pom.xml:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>my.group.id</groupId>
<artifactId>my-artifact</artifactId>
<version>0.0.1</version>
<packaging>maven-archetype</packaging>

<properties>

    <!-- Compiler properties -->
    <maven.compiler.target>1.7</maven.compiler.target>
    <maven.compiler.source>1.7</maven.compiler.source>
    <encoding>UTF-8</encoding>
    <project.build.sourceEncoding>${encoding}</project.build.sourceEncoding>
    <project.reporting.outputEncoding>${encoding}</project.reporting.outputEncoding>
    <project.resources.sourceEncoding>${encoding}</project.resources.sourceEncoding>
    <archetype.encoding>${encoding}</archetype.encoding>

    <!-- Maven plugins version -->
    <maven-archetype-plugin-version>2.2</maven-archetype-plugin-version>
    <maven-resources-plugin-version>2.6</maven-resources-plugin-version>

    <!-- Maven extentions version -->
    <maven-archetype-packaging-extension-version>2.2</maven-archetype-packaging-extension-version>
</properties>
<dependencies>
[...]
</dependencies>

<build>
    <extensions>
        <extension>
            <groupId>org.apache.maven.archetype</groupId>
            <artifactId>archetype-packaging</artifactId>
            <version>${maven-archetype-packaging-extension-version}</version>
        </extension>
    </extensions>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-resources-plugin</artifactId>
            <version>${maven-resources-plugin-version}</version>
        </plugin>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-archetype-plugin</artifactId>
            <version>${maven-archetype-plugin-version}</version>
            <extensions>true</extensions>
        </plugin>

    </plugins>

    <resources>
        <resource>
            <directory>src/main/resources</directory>
            <filtering>true</filtering>
        </resource>
    </resources>
</build>

Answer 1

You haven't set the encoding default property like this:

<project>
  ...
  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>
  ...
</project>

This approach is better than defining encoding manually for every plugin, cause all plugins having default values for encoding for example the maven-resources-plugin:

encoding:

The character encoding scheme to be applied when filtering resources.
Type: java.lang.String
Required: No
User Property: encoding
Default: ${project.build.sourceEncoding}

So this means you only need to define this property and the plugin will automatically use this encoding.