[Java] Tidy up generated code style. PR aeron-io#892.

Author: mjpt777

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

@@ -3475,12 +3475,12 @@ private void appendDecoderDisplay(
  final String groupName = formatPropertyName(groupToken.name());
  final String groupDecoderName = decoderName(groupToken.name());
 
- append(sb, indent, "int " + groupName + "OriginalOffset = " + groupName + ".offset;");
- append(sb, indent, "int " + groupName + "OriginalIndex = " + groupName + ".index;");
-
  append(
  sb, indent, "builder.append(\"" + groupName + Separator.KEY_VALUE + Separator.BEGIN_GROUP + "\");");
- append(sb, indent, groupDecoderName + " " + groupName + " = " + groupName + "();");
+ append(sb, indent, "final int " + groupName + "OriginalOffset = " + groupName + ".offset;");
+ append(sb, indent, "final int " + groupName + "OriginalIndex = " + groupName + ".index;");
+ append(sb, indent, "final " + groupDecoderName + " " + groupName + " = " + groupName + "();");
+
  append(sb, indent, "if (" + groupName + ".count() > 0)");
  append(sb, indent, "{");
  append(sb, indent, " while (" + groupName + ".hasNext())");
@@ -3490,10 +3490,11 @@ private void appendDecoderDisplay(
  append(sb, indent, " }");
  append(sb, indent, " builder.setLength(builder.length() - 1);");
  append(sb, indent, "}");
- Separator.END_GROUP.appendToGeneratedBuilder(sb, indent);
 
  append(sb, indent, groupName + ".offset = " + groupName + "OriginalOffset;");
  append(sb, indent, groupName + ".index = " + groupName + "OriginalIndex;");
+ Separator.END_GROUP.appendToGeneratedBuilder(sb, indent);
+
 
  lengthBeforeLastGeneratedSeparator = sb.length();
  Separator.FIELD.appendToGeneratedBuilder(sb, indent);