v4: add ANTLRMessage.getCause(), overridden in GrammarSyntaxMessage instead of keeping 2 separate fields

[git-p4: depot-paths = "//depot/code/antlr4/main/": change = 9210]

tool/src/org/antlr/v4/tool/ANTLRMessage.java

@@ -34,7 +34,7 @@ import java.util.Arrays;
 public class ANTLRMessage {
     public ErrorType errorType;
     public Object[] args;
-    public Throwable e;
+    private final Throwable e;
 
     // used for location template
     public String fileName;
@@ -42,20 +42,33 @@ public class ANTLRMessage {
     public int charPosition = -1;
 
     public ANTLRMessage() {
+        this(ErrorType.INVALID, (Throwable)null);
     }
 
     public ANTLRMessage(ErrorType errorType) {
-        this.errorType = errorType;
+        this(errorType, (Throwable)null);
     }
 
     public ANTLRMessage(ErrorType errorType, Object... args) {
-        this(errorType);
+        this(errorType, null, args);
+    }
+
+    public ANTLRMessage(ErrorType errorType, /*@Nullable*/ Throwable e, Object... args) {
+        this.errorType = errorType;
+        this.e = e;
         this.args = args;
     }
 
-    public ANTLRMessage(ErrorType errorType, Throwable e, Object... args) {
-        this(errorType, args);
-        this.e = e;
+    public ErrorType getErrorType() {
+        return errorType;
+    }
+
+    public Object[] getArgs() {
+        return args;
+    }
+
+    public Throwable getCause() {
+        return e;
     }
 
 	@Override

tool/src/org/antlr/v4/tool/GrammarSyntaxMessage.java

@@ -38,7 +38,6 @@ public class GrammarSyntaxMessage extends ANTLRMessage {
 	public Grammar g;
 	/** Most of the time, we'll have a token and so this will be set. */
 	public Token offendingToken;
-	public RecognitionException antlrException;
 
 	public GrammarSyntaxMessage(ErrorType etype,
 								String fileName,
@@ -46,13 +45,18 @@ public class GrammarSyntaxMessage extends ANTLRMessage {
 								RecognitionException antlrException,
 								Object... args)
 	{
-		super(etype,args);
+		super(etype, antlrException, args);
 		this.fileName = fileName;
 		this.offendingToken = offendingToken;
-		this.antlrException = antlrException;
 		if ( offendingToken!=null ) {
 			line = offendingToken.getLine();
 			charPosition = offendingToken.getCharPositionInLine();
 		}
 	}
+
+    @SuppressWarnings({"ThrowableResultOfMethodCallIgnored"})
+    @Override
+    public RecognitionException getCause() {
+        return (RecognitionException)super.getCause();
+    }
 }