Merge pull request #984 from swagger-api/retrofit_date_library_fix

set joda as default library for retrofit

Author: HugoMario

src/main/java/io/swagger/codegen/v3/generators/java/JavaClientCodegen.java

@@ -126,6 +126,10 @@ public String getHelp() {
 
     @Override
     public void processOpts() {
+        if (RETROFIT_1.equalsIgnoreCase(library)) {
+            dateLibrary = "joda";
+        }
+
         super.processOpts();
 
         if (additionalProperties.containsKey(USE_RX_JAVA)) {