Handle resolving specs without any definitions

src/main/java/io/swagger/inflector/utils/ResolverUtil.java

@@ -42,9 +42,9 @@ public Map<String, Model> getResolvedModels() {
     public void resolveFully(Swagger swagger) {
         if (swagger.getDefinitions() != null) {
             schemas = swagger.getDefinitions();
-            if (schemas == null) {
-                schemas = new HashMap<>();
-            }
+        }
+        if (schemas == null) {
+            schemas = new HashMap<>();
         }
 
         for (String name : schemas.keySet()) {

src/test/java/io/swagger/test/utils/ResolverUtilTest.java

@@ -267,4 +267,26 @@ public void testSelfReferenceResolution() {
             fail("Recursive loop found");
         }
     }
+
+
+    @Test
+    public void testResolvingWithoutDefinitions() {
+        String yaml =
+                "swagger: '2.0'\n" +
+                        "info:\n" +
+                        "  version: '1.0'\n" +
+                        "  title: No definition example\n" +
+                        "\n" +
+                        "paths:\n" +
+                        "  /:\n" +
+                        "    get:\n" +
+                        "      produces:\n" +
+                        "        - application/json\n" +
+                        "      responses:\n" +
+                        "        200:\n" +
+                        "          description: completed successfully\n";
+
+        Swagger swagger = new SwaggerParser().parse(yaml);
+        new ResolverUtil().resolveFully(swagger);
+    }
 }