[SOLVED] generic not supported in 1.3 error even when java

generic not supported in 1.3 error even when java_home points to JDK 1.7 in Maven build

I'm getting below message when I run mvn clean install

[ERROR] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Compilation failure

D:\data\work\extjs.parser\src\main\java\com\model\Component.java:[17,15] error:
generics are not supported in -source 1.3

could not parse error message:   (use -source 5 or higher to enable generics)
D:\data\work\extjs.parser\src\main\java\com\model\Container.java:14: error: gene
rics are not supported in -source 1.3
    private List<Component> items;

the project is a simple Maven project, but won't compile with generics error when I have already set JAVA_HOME to the JDK 1.7 installation path

However, when I add a plugin, then it works fine. Why is it required to explicitly set the Java home path?

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <configuration>
        <source>1.7</source>
        <target>1.7</target>
        <showDeprecation>true</showDeprecation>
        <showWarnings>true</showWarnings>
        <executable>${env.JAVA_HOME}/bin/javac</executable>
        <fork>true</fork>
    </configuration>
</plugin>

Solution

This is an old question, and after waiting for quite some time back then, I didn't get an answer. However, while browsing the Maven compiler plugin documentation, I came to know that plugin has default settings. So, earlier versions used to use JDK 1.3 as default for source/target, and now it uses 1.5. After reading docs and running mvn clean install -X, I observed that

Maven compile goal uses maven-compiler-plugin internally anyway
In POM, by specifying maven-compiler-plugin in build section, we can override certain configurations like source/target
If we don't specify, then Maven will use defaults given by maven-compiler-plugin itself, which depends on its version.

Hence there was an error as maven-compiler-plugin and its configuration (source/target) were not specified in the POM.