POM: Move Checker Framework dependencies to submodules.

Change-Id: If611d49269cce036f0c81f6b1e95bccbb53a8882
diff --git a/jgvariant-core/pom.xml b/jgvariant-core/pom.xml
index 2ddf2c4..1cb5b20 100644
--- a/jgvariant-core/pom.xml
+++ b/jgvariant-core/pom.xml
@@ -47,6 +47,20 @@
       <artifactId>apiguardian-api</artifactId>
     </dependency>
 
+    <!-- Static analysis -->
+    <dependency>
+      <groupId>org.checkerframework</groupId>
+      <artifactId>checker</artifactId>
+      <scope>provided</scope>
+      <optional>true</optional>
+    </dependency>
+    <dependency>
+      <groupId>org.checkerframework</groupId>
+      <artifactId>checker-qual</artifactId>
+      <scope>provided</scope>
+      <optional>true</optional>
+    </dependency>
+
     <!-- Testing -->
     <dependency>
       <groupId>org.junit.jupiter</groupId>