mvn clean package fails due to lack of expected license header

[elephantom]

[ERROR] Failed to execute goal org.neo4j.build.plugins:license-maven-plugin:3:check (check-licenses) on project neo4j-gremlin-plugin: Some files do not have the expected license header -> [Help 1]

I've downloaded the most recent source code and am trying to follow the instructions to use the gremlin plugin, but am coming up against the error above. The files are:

gremlin-plugin-master/src/test/java/org/neo4j/server/webadmin/console/GremlinSessionTest.java
gremlin-plugin-master/src/test/java/org/neo4j/server/webadmin/rest/ConfigureEnabledManagementConsolesGremlinTest.java
gremlin-plugin-master/src/test/java/org/neo4j/server/webadmin/rest/GremlinConsoleServiceTest.java
gremlin-plugin-master/src/test/java/org/neo4j/server/plugin/gremlin/GremlinPluginTest.java
gremlin-plugin-master/src/test/java/org/neo4j/server/plugin/gremlin/GremlinPluginFunctionalTest.java
gremlin-plugin-master/src/test/resources/graphml.xml
gremlin-plugin-master/src/site/site.xml
gremlin-plugin-master/src/data/graphml1.xml
gremlin-plugin-master/src/main/assembly/docs-assembly.xml
gremlin-plugin-master/src/main/assembly/server-plugin.xml
gremlin-plugin-master/src/main/java/org/neo4j/server/webadmin/console/GremlinWebConsole.java
gremlin-plugin-master/src/main/java/org/neo4j/server/webadmin/console/GremlinSession.java
gremlin-plugin-master/src/main/java/org/neo4j/server/webadmin/console/GremlinResultHook.java
gremlin-plugin-master/src/main/java/org/neo4j/server/webadmin/console/Neo4jGroovyImports.java
gremlin-plugin-master/src/main/java/org/neo4j/server/webadmin/console/GremlinSessionCreator.java
gremlin-plugin-master/src/main/java/org/neo4j/server/plugin/gremlin/ScriptCountingEngineReplacementDecision.java
gremlin-plugin-master/src/main/java/org/neo4j/server/plugin/gremlin/CountingEngineReplacementDecision.java
gremlin-plugin-master/src/main/java/org/neo4j/server/plugin/gremlin/EngineReplacementDecision.java
gremlin-plugin-master/src/main/java/org/neo4j/server/plugin/gremlin/GremlinPlugin.java
gremlin-plugin-master/src/main/java/org/neo4j/server/rest/repr/GremlinMapRepresentation.java
gremlin-plugin-master/src/main/java/org/neo4j/server/rest/repr/GremlinObjectToRepresentationConverter.java
gremlin-plugin-master/src/main/java/org/neo4j/server/rest/repr/GremlinTableRepresentation.java