Use an empty set instead of null.

Theo Zourzouvillys · Theo Zourzouvillys · commit 9895ced86ad0 · 2015-09-24T19:33:20.000-06:00
diff --git a/src/main/java/graphql/schema/GraphQLSchema.java b/src/main/java/graphql/schema/GraphQLSchema.java
@@ -5,10 +5,12 @@
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
+import graphql.Assert;
 import graphql.Directives;
 
 public class GraphQLSchema {
@@ -19,14 +21,15 @@ public class GraphQLSchema {
     private Set<GraphQLType> dictionary;
 
     public GraphQLSchema(GraphQLObjectType queryType) {
-        this(queryType, null, null);
+        this(queryType, null, Collections.<GraphQLType>emptySet());
     }
 
     public Set<GraphQLType> getDictionary() {
       return dictionary;
     }
 
     public GraphQLSchema(GraphQLObjectType queryType, GraphQLObjectType mutationType, Set<GraphQLType> dictionary) {
+        assertNotNull(dictionary, "dictionary can't be null");
         assertNotNull(queryType, "queryType can't be null");
         this.queryType = queryType;
         this.mutationType = mutationType;
@@ -86,10 +89,11 @@ public Builder mutation(GraphQLObjectType mutationType) {
         }
 
         public GraphQLSchema build() {
-          return build(null);
+          return build(Collections.<GraphQLType>emptySet());
       }
 
         public GraphQLSchema build(Set<GraphQLType> dictionary) {
+          Assert.assertNotNull(dictionary, "dictionary can't be null");
           GraphQLSchema graphQLSchema = new GraphQLSchema(queryType, mutationType, dictionary);
           new SchemaUtil().replaceTypeReferences(graphQLSchema);
           return graphQLSchema;
diff --git a/src/test/groovy/graphql/schema/SchemaUtilTest.groovy b/src/test/groovy/graphql/schema/SchemaUtilTest.groovy
@@ -3,6 +3,8 @@ package graphql.schema
 import graphql.introspection.Introspection
 import spock.lang.Specification
 
+import java.util.Collections;
+
 import static graphql.Scalars.GraphQLBoolean
 import static graphql.Scalars.GraphQLString
 import static graphql.StarWarsSchema.*
@@ -11,7 +13,7 @@ class SchemaUtilTest extends Specification {
 
     def "collectAllTypes"() {
         when:
-        Map<String, GraphQLType> types = new SchemaUtil().allTypes(starWarsSchema, null)
+        Map<String, GraphQLType> types = new SchemaUtil().allTypes(starWarsSchema, Collections.emptySet())
         then:
         types == [(droidType.name)                 : droidType,
                   (humanType.name)                 : humanType,
