Fix an ArrayToString false positive for the varargs overload of Joiner.join(Object, Object, Object...)

#4233 (review)

PiperOrigin-RevId: 619537499

Author: cushon

core/src/main/java/com/google/errorprone/bugpatterns/AbstractToString.java

@@ -201,8 +201,9 @@ public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState
                 argTree,
                 ToStringKind.IMPLICIT,
                 state);
+          } else {
+            handleStringifiedTree(argTree, ToStringKind.IMPLICIT, state);
           }
-          handleStringifiedTree(argTree, ToStringKind.IMPLICIT, state);
         }
       }
     }

core/src/test/java/com/google/errorprone/bugpatterns/ArrayToStringTest.java

@@ -199,4 +199,33 @@ public void arrayPassedToJoiner() {
             "}")
         .doTest();
   }
+
+  @Test
+  public void arrayPassedToJoiner_firstSecondRest_negative() {
+    compilationHelper
+        .addSourceLines(
+            "Test.java",
+            "import com.google.common.base.Joiner;",
+            "class Test {",
+            "  String test(Joiner j, Object first, Object second, Object[] rest) {",
+            "    return j.join(first, second, rest);",
+            "  }",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  public void arrayPassedToJoiner_firstSecondRest_positive() {
+    compilationHelper
+        .addSourceLines(
+            "Test.java",
+            "import com.google.common.base.Joiner;",
+            "class Test {",
+            "  String test(Joiner j, Object first, Object second, Object third, Object[] rest) {",
+            "    // BUG: Diagnostic contains:",
+            "    return j.join(first, second, third, rest);",
+            "  }",
+            "}")
+        .doTest();
+  }
 }