fixed handling of empty mapping

Author: hauner

src/main/groovy/com/github/hauner/openapi/spring/generatr/MappingConverter.groovy

@@ -45,19 +45,19 @@ class MappingConverter {
     List<Mapping> convert (YamlMapping source) {
         def result = new ArrayList<Mapping>()
 
-        source.map.types.each {
+        source?.map?.types?.each {
             result.add (convertType (it))
         }
 
-        source.map.parameters.each {
+        source?.map?.parameters?.each {
             result.add (convertParameter (it))
         }
 
-        source.map.responses.each {
+        source?.map?.responses?.each {
             result.add (convertResponse (it))
         }
 
-        source.map.paths.each {
+        source?.map?.paths?.each {
             result.add(convertPath (it.key, it.value))
         }
 

src/test/groovy/com/github/hauner/openapi/spring/generatr/MappingConverterSpec.groovy

@@ -316,4 +316,15 @@ map:
         exclude << [true, false]
     }
 
+    void "handles empty mapping" () {
+        String yaml = ""
+
+        when:
+        def mapping = reader.read (yaml)
+        def mappings = converter.convert (mapping)
+
+        then:
+        mappings.size() == 0
+    }
+
 }