Force Java 7 compatibility

Author: pvdissel

subprojects/api/api.gradle

@@ -1,9 +1,14 @@
+import static org.gradle.api.JavaVersion.VERSION_1_7
+
 apply plugin: 'java'
 apply plugin: 'groovy'
 apply from: script('integrationTest')
 
 description = 'Bol.com OpenAPI v4 HTTP Client'
 
+targetCompatibility = VERSION_1_7
+sourceCompatibility = VERSION_1_7
+
 dependencies {
     compile project(':schema')
     compile libraries.feign

subprojects/client/client.gradle

@@ -1,9 +1,14 @@
+import static org.gradle.api.JavaVersion.VERSION_1_7
+
 apply plugin: 'java'
 apply plugin: 'groovy'
 apply from: script('integrationTest')
 
 description = 'Bol.com OpenAPI v4 client'
 
+targetCompatibility = VERSION_1_7
+sourceCompatibility = VERSION_1_7
+
 dependencies {
     compile project(':api')
 

subprojects/schema/schema.gradle

@@ -1,8 +1,13 @@
+import static org.gradle.api.JavaVersion.VERSION_1_7
+
 apply from: script('jaxb')
 apply plugin: 'groovy'
 
 description = 'OpenAPI v4 Schema'
 
+targetCompatibility = VERSION_1_7
+sourceCompatibility = VERSION_1_7
+
 dependencies {
     testCompile libraries.spock
     testCompile libraries.hamcrest