diff --git a/documentation/docs/06_extend-tutorial-data-processors.md b/documentation/docs/06_extend-tutorial-data-processors.md
index 408159b..b4be1db 100644
--- a/documentation/docs/06_extend-tutorial-data-processors.md
+++ b/documentation/docs/06_extend-tutorial-data-processors.md
@@ -183,8 +183,8 @@
 Next, we are interested in the fields of the input event stream that contains the latitude and longitude value we would like to compute against the geofence center location as follows:
 
 ```java
-String latitudeFieldName = extractor.mappingPropertyValue("latitude-field");
-String longitudeFieldName = extractor.mappingPropertyValue("longitude-field");
+String latitudeFieldName = parameters.extractor().mappingPropertyValue("latitude-field");
+String longitudeFieldName = parameters.extractor().mappingPropertyValue("longitude-field");
 ```
 
 We use the same `internalId` we've used to define the mapping property requirements in the `declareModel` method.
@@ -232,6 +232,9 @@
 
  private float centerLatitude;
  private float centerLongitude;
+ private String latitudeFieldName;
+ private String longitudeFieldName;
+ 
  private int radius;
 
  @Override
@@ -257,9 +260,13 @@
  }
 
  @Override
- public void onInvocation(ProcessorParams parameters, SpOutputCollector spOutputCollector, EventProcessorRuntimeContext runtimeContext) throws SpRuntimeException {
+ public void onInvocation(ProcessorParams parameters, 
+                          SpOutputCollector spOutputCollector, 
+                          EventProcessorRuntimeContext runtimeContext) throws SpRuntimeException {
   this.centerLatitude = parameters.extractor().singleValueParameter(LATITUDE_CENTER, Float.class);
   this.centerLongitude = parameters.extractor().singleValueParameter(LONGITUDE_CENTER, Float.class);
+  this.latitudeFieldName = parameters.extractor().mappingPropertyValue("latitude-field");
+  this.longitudeFieldName = parameters.extractor().mappingPropertyValue("longitude-field");
   this.radius = parameters.extractor().singleValueParameter("radius", Integer.class);
  }