[C++ Generator]:Incorrect generation of arrays within groups

Author: acarlile

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/cpp/CppGenerator.java

@@ -161,7 +161,7 @@ private void generateGroups(final StringBuilder sb, final List<Token> tokens, fi
 
             final List<Token> fields = new ArrayList<>();
             i = collectFields(tokens, i, fields);
-            sb.append(generateFields(groupName, fields, indent + INDENT));
+            sb.append(generateFields(formatClassName(groupName), fields, indent + INDENT));
 
             final List<Token> groups = new ArrayList<>();
             i = collectGroups(tokens, i, groups);