Downgrade maven-compiler-plugin to 3.8.1

Newer versions cause a lengthy delay before compilation
begins in some scenarios where module-info.java is present.

pom.xml

@@ -269,7 +269,12 @@
 		<maven-antrun-plugin.version>3.1.0</maven-antrun-plugin.version>
 		<maven-assembly-plugin.version>3.6.0</maven-assembly-plugin.version>
 		<maven-clean-plugin.version>3.3.1</maven-clean-plugin.version>
-		<maven-compiler-plugin.version>3.10.1</maven-compiler-plugin.version>
+		<!--
+		NB: Versions of the maven-compiler-plugin newer than 3.8.1 cause very
+		slow compilation preparation (30-60 seconds or longer) for some
+		SciJava components, during parsing of module-info.java files.
+		-->
+		<maven-compiler-plugin.version>3.8.1</maven-compiler-plugin.version>
 		<maven-dependency-plugin.version>3.6.0</maven-dependency-plugin.version>
 		<maven-deploy-plugin.version>3.1.1</maven-deploy-plugin.version>
 		<maven-enforcer-plugin.version>3.3.0</maven-enforcer-plugin.version>