enforce 1.8 language level,closes #218

Author: Alexander Furer

build.gradle

@@ -44,6 +44,9 @@ subprojects {
 
     sourceCompatibility = 1.8
     targetCompatibility = 1.8
+    tasks.withType(JavaCompile,{
+        options.compilerArgs.addAll(["--release", "8"])
+    })
 
     test {
      //   forkEvery = 1

grpc-spring-boot-starter/src/main/java/org/lognet/springboot/grpc/autoconfigure/NettyServerBuilderSelector.java

@@ -39,9 +39,9 @@ public String[] selectImports(AnnotationMetadata importingClassMetadata) {
                     .orElse(true);
             imports.add(preferShadedNetty ? shadedNettyConfig : pureNettyConfig);
         }else {
-            Optional
-                    .ofNullable(shadedNettyConfig)
-                    .or(()->Optional.ofNullable(pureNettyConfig))
+            final String cfg = Optional.ofNullable(shadedNettyConfig)
+                    .orElse(Optional.ofNullable(pureNettyConfig).orElse(null));
+            Optional.ofNullable(cfg)
                     .ifPresent(imports::add);
         }