diff --git a/core/pom.xml b/core/pom.xml
index 32bfca798..3900bb6b1 100644
--- a/core/pom.xml
+++ b/core/pom.xml
@@ -83,6 +83,7 @@
       <plugin>
         <artifactId>maven-javadoc-plugin</artifactId>
         <configuration>
+          <source>8</source>
           <encoding>UTF-8</encoding>
           <docencoding>UTF-8</docencoding>
           <charset>UTF-8</charset>