Add detail to DataTable hint in JavaSnippet and update test (#1298)

* Add details to DataTable hint in JavaSnippet and update unit test

Author: mlvandijk

java/src/main/java/cucumber/runtime/java/AbstractJavaSnippet.java

@@ -24,7 +24,9 @@ public String arguments(List<Class<?>> argumentTypes) {
     public String tableHint() {
         return "    // For automatic transformation, change DataTable to one of\n" +
                 "    // List<YourType>, List<List<E>>, List<Map<K,V>> or Map<K,V>.\n" +
-                "    // E,K,V must be a scalar (String, Integer, Date, enum etc)\n";
+                "    // E,K,V must be a scalar (String, Integer, Date, enum etc).\n" +
+                "    // Field names for YourType must match the column names in \n" +
+                "    // your feature file (except for spaces and capitalization).\n";
     }
 
     @Override

java/src/test/java/cucumber/runtime/java/JavaSnippetTest.java

@@ -153,7 +153,9 @@ public void generatesSnippetWithDataTable() {
                 "    // Write code here that turns the phrase above into concrete actions\n" +
                 "    // For automatic transformation, change DataTable to one of\n" +
                 "    // List<YourType>, List<List<E>>, List<Map<K,V>> or Map<K,V>.\n" +
-                "    // E,K,V must be a scalar (String, Integer, Date, enum etc)\n" +
+                "    // E,K,V must be a scalar (String, Integer, Date, enum etc).\n" +
+                "    // Field names for YourType must match the column names in \n" +
+                "    // your feature file (except for spaces and capitalization).\n" +
                 "    throw new PendingException();\n" +
                 "}\n";
         PickleTable dataTable = new PickleTable(asList(new PickleRow(asList(new PickleCell(null, "col1")))));