Bump maven-compiler-plugin from 3.8.1 to 3.9.0 in /core

Bumps [maven-compiler-plugin](https://github.com/apache/maven-compiler-plugin) from 3.8.1 to 3.9.0.
- [Release notes](https://github.com/apache/maven-compiler-plugin/releases)
- [Commits](https://github.com/apache/maven-compiler-plugin/compare/maven-compiler-plugin-3.8.1...maven-compiler-plugin-3.9.0)

---
updated-dependencies:
- dependency-name: org.apache.maven.plugins:maven-compiler-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Closes #306

Change-Id: I71846300f3fe3ad45a0ce7185842147b270c13c0
diff --git a/core/pom.xml b/core/pom.xml
index e80010d..8026baa 100644
--- a/core/pom.xml
+++ b/core/pom.xml
@@ -52,7 +52,7 @@
 			<plugin>
 				<groupId>org.apache.maven.plugins</groupId>
 				<artifactId>maven-compiler-plugin</artifactId>
-				<version>3.8.1</version>
+				<version>3.9.0</version>
 				<configuration>
 					<compilerVersion>${java.version}</compilerVersion>
 					<source>${java.version}</source>