Make fields final where possible

Author: cirras

delphi-frontend/src/main/java/au/com/integradev/delphi/preprocessor/directive/expression/ExpressionLexer.java

@@ -429,7 +429,7 @@ private static boolean isBinaryDigit(char character) {
 
   private final class NumberReader {
     private TokenType type;
-    private StringBuilder value = new StringBuilder();
+    private final StringBuilder value = new StringBuilder();
     private Predicate<Character> isDigitCharacter;
     private boolean canBeReal;
 

delphi-frontend/src/main/java/au/com/integradev/delphi/type/factory/StructTypeImpl.java

@@ -46,7 +46,7 @@ public class StructTypeImpl extends GenerifiableTypeImpl implements StructType {
   private Set<Type> ancestorList;
   private StructKind kind;
   private Type parent;
-  private List<Type> attributeTypes;
+  private final List<Type> attributeTypes;
 
   StructTypeImpl(
       List<ImagePart> imageParts,

delphi-frontend/src/main/java/au/com/integradev/delphi/type/intrinsic/IntrinsicRoutine.java

@@ -134,7 +134,7 @@ IntrinsicParameterData build(DelphiScope scope) {
 
   static final class Builder {
     private final String routineName;
-    private List<IntrinsicParameterData.Builder> parameters;
+    private final List<IntrinsicParameterData.Builder> parameters;
     private IntrinsicParameterData.Builder variadicParameter;
     private int requiredParameters;
     private Type returnType;