Why does maven not copy the properties files during the build process?

What is your project's build path configured to be in Netbeans? You might try changing it to src/main/webapp/WEB-INF/classes. This way class files compiled from your src/main/java folder and any resources you have under src/main/resources should get included in the generated WAR. You would then be able to access your config.properties file if you place it under the src/main/resources folder.

You might also review any includes sections in your pom.xml and ensure you're not accidentally excluding something (if you explicitly include some things, you're likely implicitly excluding everything else).

By default maven will include all files under resources folder. If your properties files are not in the resource folder, then you need to include the following in the pom.xml file under the build section.

<build>
/* other tags like <plugins> goes here */
<sourceDirectory>src/main/java</sourceDirectory>  
    <resources>
        <resource>
            <directory>src/main/java</directory>
            <includes>
                <include>**/*.xml</include>
            </includes>
        </resource>
    </resources>
/* other tags like <plugins> goes here */
</build>

Maven doesn't copy resources from the java source tree by default, but you can get it do that by adding this to your pom.xml:

<build>
  <resources>
    <resource>
      <directory>src/main/java</directory>
      <excludes><exclude>**/*.java</exclude></excludes>
    </resource>
  </resources>
</build>

Make sure you exclude the java source files.

From https://rogerkeays.com/how-to-change-mavens-default-resource-folder