[java] Adjust grammar for text blocks

Refs #1973

pmd-java/etc/grammar/Java.jjt

@@ -491,7 +491,8 @@ TOKEN_MGR_DECLS :
 
 SPECIAL_TOKEN :
 {
-  " " | "\t" | "\n" | "\r" | "\f"
+  < HORIZONTAL_WHITESPACE: [" ", "\t", "\f"] >
+| < LINE_TERMINATOR: "\n" | "\r" | "\r\n" >
 }
 
 SPECIAL_TOKEN :
@@ -655,34 +656,28 @@ TOKEN :
       )
       "'"
   >
+| < #STRING_ESCAPE:
+      "\\"
+      ( ["n","t","b","r","f","\\","'","\""]
+      // octal escapes
+      | ["0"-"7"] ( ["0"-"7"] )?
+      | ["0"-"3"] ["0"-"7"] ["0"-"7"]
+      )
+  >
 |
   < STRING_LITERAL:
       "\""
       (   (~["\"","\\","\n","\r"])
-        | ("\\"
-            ( ["n","t","b","r","f","\\","'","\""]
-            | ["0"-"7"] ( ["0"-"7"] )?
-            | ["0"-"3"] ["0"-"7"] ["0"-"7"]
-            )
-          )
+        | <STRING_ESCAPE>
       )*
       "\""
   >
-}
-
-MORE :
-{
-    < "\"\"\"" > : IN_TEXT_BLOCK
-}
-
-<IN_TEXT_BLOCK> TOKEN :
-{
-    < TEXT_BLOCK_LITERAL: "\"\"\""> : DEFAULT
-}
-
-<IN_TEXT_BLOCK> MORE :
-{
-    < ~[] >
+|
+  < TEXT_BLOCK_LITERAL:
+     "\"\"\"" (<HORIZONTAL_WHITESPACE>)* <LINE_TERMINATOR>
+        ( ~["\"", "\\"] | "\"" ~["\""] | "\"\"" ~["\""] | <STRING_ESCAPE> )*
+     "\"\"\""
+  >
 }
 
 /* IDENTIFIERS */

pmd-java/src/test/java/net/sourceforge/pmd/lang/java/ast/Java13Test.java

@@ -74,7 +74,7 @@ public class Java13Test {
         ASTCompilationUnit compilationUnit = ParserTstUtil.parseAndTypeResolveJava("13", loadSource("TextBlocks.java"));
         Assert.assertNotNull(compilationUnit);
         List<ASTLiteral> literals = compilationUnit.findDescendantsOfType(ASTLiteral.class);
-        Assert.assertEquals(9, literals.size());
+        Assert.assertEquals(10, literals.size());
         for (int i = 0; i < 8; i++) {
             ASTLiteral literal = literals.get(i);
             Assert.assertTrue(literal.isTextBlock());
@@ -83,6 +83,7 @@ public class Java13Test {
                 + "                        <p>Hello, world</p>\n" + "                    </body>\n"
                 + "                </html>\n" + "                \"\"\"", literals.get(0).getImage());
         Assert.assertFalse(literals.get(8).isTextBlock());
+        Assert.assertTrue(literals.get(9).isTextBlock());
     }
 
     @Test(expected = ParseException.class)

pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/ast/jdkversiontests/java13/TextBlocks.java

@@ -44,5 +44,12 @@ public class TextBlocks {
                            """;  // the two characters \ LF
 
         String normalStringLiteral = "test";
+
+        String code = 
+            """
+            String text = \"""
+                A text block inside a text block
+            \""";
+            """;
     }
 }