Issue checkstyle#12486: NoWhitespaceAfter don't check synchronized me…

…thod

src/main/java/com/puppycrawl/tools/checkstyle/checks/whitespace/NoWhitespaceAfterCheck.java

@@ -284,7 +284,10 @@ private static DetailAST getWhitespaceFollowedNode(DetailAST ast) {
      */
     private static boolean shouldCheckWhitespaceAfter(DetailAST ast) {
         final DetailAST previousSibling = ast.getPreviousSibling();
-        return previousSibling == null || previousSibling.getType() != TokenTypes.ANNOTATIONS;
+        final boolean isSynchronizedMethod = ast.getType() == TokenTypes.LITERAL_SYNCHRONIZED
+                        && ast.getFirstChild() == null;
+        return (previousSibling == null || previousSibling.getType() != TokenTypes.ANNOTATIONS)
+                && !isSynchronizedMethod;
     }
 
     /**

src/test/java/com/puppycrawl/tools/checkstyle/checks/whitespace/NoWhitespaceAfterCheckTest.java

@@ -354,6 +354,17 @@ public void testNoWhitespaceAfterWithEmoji() throws Exception {
                 getPath("InputNoWhitespaceAfterWithEmoji.java"), expected);
     }
 
+        @Test
+    public void testNoWhitespaceAfterSynchronized() throws Exception {
+
+        final String[] expected = {
+            "18:9: " + getCheckMessage(MSG_KEY, "synchronized"),
+        };
+
+        verifyWithInlineConfigParser(
+                getPath("InputNoWhitespaceAfterSynchronized.java"), expected);
+    }
+
     /**
      * Creates MOCK lexical token and returns AST node for this token.
      *

src/test/resources/com/puppycrawl/tools/checkstyle/checks/whitespace/nowhitespaceafter/InputNoWhitespaceAfterSynchronized.java

@@ -0,0 +1,53 @@
+/*
+NoWhitespaceAfter
+allowLineBreaks = (default)true
+tokens = LITERAL_SYNCHRONIZED
+
+
+*/
+package com.puppycrawl.tools.checkstyle.checks.whitespace.nowhitespaceafter;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Target;
+
+public class InputNoWhitespaceAfterSynchronized<T> {
+
+    private final Object lock = new Object();
+
+    void m1() {
+        synchronized (lock) {} // violation
+        synchronized(lock) {} // ok
+    }
+
+    synchronized int m2() { // ok
+        return 2;
+    }
+
+    synchronized private int[] m3() { // ok
+        return new int[]{2};
+    }
+
+    synchronized int[] m4() { // ok
+        return new int[]{2};
+    }
+
+    private final synchronized int m5() { // ok
+        return 2;
+    }
+
+    synchronized T m6() { // ok
+        return null;
+    }
+
+    @SyncAnno synchronized T m7() { // ok
+        return null;
+    }
+
+    @SyncAnno private synchronized T m8() { // ok
+        return null;
+    }
+}
+
+@Target(ElementType.METHOD)
+@interface SyncAnno {
+}