Handle correctly the case of no default response (see comment in #1124)

modules/swagger-codegen/src/main/java/io/swagger/codegen/CodegenOperation.java

@@ -12,7 +12,7 @@ public class CodegenOperation {
     public final List<CodegenProperty> responseHeaders = new ArrayList<CodegenProperty>();
     public Boolean hasConsumes, hasProduces, hasParams, returnTypeIsPrimitive,
             returnSimpleType, subresourceOperation, isMapContainer, isListContainer,
-            hasMore = Boolean.TRUE, isMultipart;
+            hasMore = Boolean.TRUE, isMultipart, isResponseBinary = Boolean.FALSE;
     public String path, operationId, returnType, httpMethod, returnBaseType,
             returnContainer, summary, notes, baseName, defaultResponse;
     public List<Map<String, String>> consumes, produces;

modules/swagger-codegen/src/main/java/io/swagger/codegen/CodegenResponse.java

@@ -15,7 +15,7 @@ public class CodegenResponse {
     public Boolean primitiveType;
     public Boolean isMapContainer;
     public Boolean isListContainer;
-    public Boolean isBinary;
+    public Boolean isBinary = Boolean.FALSE;
     public Object schema;
     public String jsonSchema;
 

modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java

@@ -835,6 +835,9 @@ public class DefaultCodegen {
                 }
                 r.isDefault = response == methodResponse;
                 op.responses.add(r);
+                if (r.isBinary && r.isDefault){
+                    op.isResponseBinary = Boolean.TRUE;
+                }
             }
             op.responses.get(op.responses.size() - 1).hasMore = false;