support method getVarFieldName for UTF similar to Ascii.

Author: ariksher-nex

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

@@ -904,6 +904,28 @@ private void generateDataDecodeMethods(
                     generateGet(lengthType, "limit", byteOrderStr),
                     byteOrderStr);
             }
+            if (characterEncoding.contains("UTF8"))
+            {
+                new Formatter(sb).format("\n" +
+                    indent + "    public int get%1$s(final Appendable appendable)\n" +
+                    indent + "    {\n" +
+                    "%2$s" +
+                    indent + "        final int headerLength = %3$d;\n" +
+                    indent + "        final int limit = parentMessage.limit();\n" +
+                    indent + "        final int dataLength = (int)%4$s;\n" +
+                    indent + "        final int dataOffset = limit + headerLength;\n\n" +
+                    indent + "        parentMessage.limit(dataOffset + dataLength);\n" +
+                    indent + "        appendable.append(buffer.getStringWithoutLengthUtf8(dataOffset, dataLength));\n\n" +
+                    //TODO: wait for signature below, similar to getStringWithoutLengthAscii(offset,length,appendable)
+                    indent + "        //buffer.getStringWithoutLengthUtf8(dataOffset, dataLength, appendable);\n\n" +
+                    indent + "        return dataLength;\n" +
+                    indent + "    }\n",
+                    Generators.toUpperFirstChar(propertyName),
+                    generateStringNotPresentConditionForAppendable(token.version(), indent),
+                    sizeOfLengthField,
+                    generateGet(lengthType, "limit", byteOrderStr),
+                    byteOrderStr);
+            }
         }
     }