Use BOM from Gradle plugin management

We use a BOM to share our dependency management in MyCompany.

It is defined as a Maven POM. Here is a minimal example:

<?xml version="1.0" encoding="UTF-8"?>
<project>
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.mycompany.common</groupId>
  <artifactId>common-java</artifactId>
  <version>1.0.0</version>
  <packaging>pom</packaging>

  <properties>
    <spring-boot.version>2.4.0</spring-boot.version>
  </properties>

  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-dependencies</artifactId>
        <version>${spring-boot.version}</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
    </dependencies>
  </dependencyManagement>

</project>

It is then used from Gradle projects.

Although this works for code dependencies, I'd like to find out a way to use it from plugin management.

For now, we define in settings.gradle.kts:

pluginManagement {

    val springBootVersion: String by settings

    plugins {
        id("org.springframework.boot") version(springBootVersion)
    }
}

springBootVersion being defined in the gradle.properties.

This is an issue to me because Spring version is defined both:

• in the shared BOM;
• in each project's plugin management.

How can I access to that BOM from Gradle's plugin management? And if I can't, what is a good don't-repeat-yourself practice to do so?