fix(protocol): change custom headers to Map<String,String>

BREAKING CHANGE:
- Return type of 'getCustomHeaders' in JobRecord and clients'
ActivateJobs response was changed from Map<String, Object> to
Map<String, String>

broker-core/src/main/java/io/zeebe/broker/exporter/ExporterObjectMapper.java

@@ -34,6 +34,8 @@ public class ExporterObjectMapper {
 
   private static final TypeReference<Map<String, Object>> MAP_TYPE_REFERENCE =
       new TypeReference<Map<String, Object>>() {};
+  private static final TypeReference<Map<String, Object>> STRING_MAP_TYPE_REFERENCE =
+      new TypeReference<Map<String, Object>>() {};
 
   private final ObjectMapper msgpackObjectMapper;
   private final ObjectMapper jsonObjectMapper;
@@ -105,4 +107,12 @@ public Map<String, Object> fromMsgpackAsMap(InputStream inputStream) {
       throw new RuntimeException("Failed deserialize Msgpack JSON to map", e);
     }
   }
+
+  public Map<String, String> fromMsgpackAsStringMap(InputStream inputStream) {
+    try {
+      return msgpackObjectMapper.readValue(inputStream, STRING_MAP_TYPE_REFERENCE);
+    } catch (IOException e) {
+      throw new RuntimeException("Failed deserialize Msgpack JSON to map", e);
+    }
+  }
 }

clients/go/entities/job.go

@@ -32,8 +32,8 @@ func (job *Job) GetVariablesAs(variablesType interface{}) error {
 	return json.Unmarshal([]byte(job.Variables), variablesType)
 }
 
-func (job *Job) GetCustomHeadersAsMap() (map[string]interface{}, error) {
-	var customHeadersMap map[string]interface{}
+func (job *Job) GetCustomHeadersAsMap() (map[string]string, error) {
+	var customHeadersMap map[string]string
 	return customHeadersMap, job.GetCustomHeadersAs(&customHeadersMap)
 }
 

clients/go/entities/job_test.go

@@ -31,6 +31,10 @@ var (
 		"foo":   "bar",
 		"hello": "world",
 	}
+    expectedJsonAsMapVariables = map[string]interface{}{
+        "foo":   "bar",
+        "hello": "world",
+    }
 	expectedJsonAsStruct = MyType{
 		Foo:   "bar",
 		Hello: "world",
@@ -46,7 +50,7 @@ func TestJob_GetVariablesAsMap(t *testing.T) {
 	if err != nil {
 		t.Error("Failed to get variables as map", err)
 	}
-	if reflect.DeepEqual(variables, expectedJsonAsMap) {
+	if !reflect.DeepEqual(variables, expectedJsonAsMapVariables) {
 		t.Error("Failed to get variables as map, got", variables, "instead of", expectedJsonAsMap)
 	}
 }
@@ -66,7 +70,7 @@ func TestJob_GetCustomHeadersAsMap(t *testing.T) {
 	if err != nil {
 		t.Error("Failed to get custom headers as map", err)
 	}
-	if reflect.DeepEqual(customHeaders, expectedJsonAsMap) {
+	if !reflect.DeepEqual(customHeaders, expectedJsonAsMap) {
 		t.Error("Failed to get custom headers as map, got", customHeaders, "instead of", expectedJsonAsMap)
 	}
 }