Use gradle-versions-plugin to check for dependency updates.

.travis.yml

@@ -1,3 +1,4 @@
+dist: trusty
 language: java
 jdk:
  - oraclejdk8

build.gradle

@@ -7,13 +7,15 @@ buildscript {
     }
     dependencies {
         classpath("org.springframework.boot:spring-boot-gradle-plugin:2.0.0.RELEASE")
+        classpath("com.github.ben-manes:gradle-versions-plugin:0.27.0")
     }
 }
 
 
 group = 'opacapi'
 version = '1.0-SNAPSHOT'
 
+apply from: 'gradle/gradle-versions.gradle'
 apply plugin: 'java'
 apply plugin: 'idea'
 apply plugin: 'application'

gradle/gradle-versions.gradle

@@ -0,0 +1,19 @@
+// Gradle Versions Plugin
+
+apply plugin: "com.github.ben-manes.versions"
+
+dependencyUpdates {
+
+    def isNonStable = { String version ->
+        def stableKeyword = ["RELEASE", "FINAL", "GA"].any {
+            qualifier -> version.toUpperCase().contains(qualifier)
+        }
+        def regex = /^[0-9,.v-]+(-r)?$/
+        return !stableKeyword && !(version ==~ regex)
+    }
+
+    rejectVersionIf {
+        isNonStable(it.candidate.version)
+    }
+
+}