build-helper-maven-plugin on profile doesn't work

[provide a description of the issue]

Dear support,
I am trying to use the profiles in a POM to add extra source directory.
I am using a plugin which generate java code in a custom directory target/generated-sources/plc4x and for telling VSC that this directory has sono code I would like to use build-helper-maven-plugin.

If I use the plugin inside the POM it works:

  <build>
    <plugins>
      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>build-helper-maven-plugin</artifactId>
        <executions>
          <execution>
            <id>add-source</id>
            <phase>generate-sources</phase>
            <goals>
              <goal>add-source</goal>
            </goals>
            <configuration>
              <sources>
                <source>target/generated-sources/plc4x</source>
              </sources>
            </configuration>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>

In this way VSC add correctly the new directory in the .classpath file:

        <classpathentry kind="src" output="target/classes" path="target/generated-sources/plc4x">
                <attributes>
                        <attribute name="optional" value="true"/>
                        <attribute name="maven.pomderived" value="true"/>
                </attributes>
        </classpathentry>

but if I try to use profiles to handle the plugin just in some circumstances, it doesn't work:

<profiles>
<profile>
      <id>vsc</id>
      <activation>
        <os>
          <family>mac</family>
        </os>
      </activation>
            <build>
        <pluginManagement>
          <plugins>
            <plugin>
              <groupId>org.codehaus.mojo</groupId>
              <artifactId>build-helper-maven-plugin</artifactId>
              <executions>
                <execution>
                  <id>add-source</id>
                  <phase>generate-sources</phase>
                  <goals>
                    <goal>add-source</goal>
                  </goals>
                  <configuration>
                    <sources>
                      <source>target/generated-sources/plc4x</source>
                    </sources>
                  </configuration>
                </execution>
              </executions>
            </plugin>
          </plugins>
        </pluginManagement>
      </build>
</profile>
</profiles>

In this way the entry in the .classpath file is not present.

Environment

• Operating System: Mac Os 11.2
• JDK version: openjdk version "13.0.2" 2020-01-14
• Visual Studio Code version: 1.53.0

Current Result

I can't use profiles to handle the build-helper-maven-plugin

Expected Result

To have the the path entry in the classpath in both the situation

Regards,
Stefano Bossi

Tái hiện hai cấu hình POM trên macOS với các phiên bản JDK và VS Code được liệt kê, so sánh mục .classpath được tạo ra khi build-helper-maven-plugin nằm dưới build và khi nó nằm trong một profile được kích hoạt theo hệ điều hành. Bắt đầu với việc xử lý profile của Maven và việc nhập dự án Java vào VS Code; được xem là hoàn tất khi đường dẫn nguồn đã tạo xuất hiện trong .classpath ở cả hai tình huống được báo cáo.