try building with JDK9 on travis (will revert Publisher change)

Author: ktoso

.java-version

@@ -0,0 +1 @@
+9-ea

.travis.yml

@@ -1,12 +1,15 @@
 language: java
 sudo: required
+dist: trusty
+group: edge
 script:
   - ./gradlew check
 cache:
   directories:
   - $HOME/.gradle
 jdk:
   - oraclejdk8
+  - oraclejdk9
   - openjdk6
 env:
   global:

api/src/main/java/org/reactivestreams/Publisher.java

@@ -11,6 +11,10 @@
 
 package org.reactivestreams;
 
+// FIXME THIS IS ONLY TO CHECK THAT JDK9 BUILD WORKED ON TRAVIS
+import java.util.concurrent.Flow; // REMOVE THIS
+// FIXME THIS IS ONLY TO CHECK THAT JDK9 BUILD WORKED ON TRAVIS
+
 /**
  * A {@link Publisher} is a provider of a potentially unbounded number of sequenced elements, publishing them according to
  * the demand received from its {@link Subscriber}(s).