fixes #917

Author: wumpz

src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt

@@ -3308,7 +3308,7 @@ WhenClause WhenThenSearchCondition():
 }
 {
     <K_WHEN> (LOOKAHEAD(Expression()) whenExp=Expression() | whenExp=SimpleExpression()) 
-        <K_THEN> thenExp=Condition()
+        <K_THEN> thenExp=Expression()
     {
        whenThen.setWhenExpression(whenExp);
        whenThen.setThenExpression(thenExp);

src/test/java/net/sf/jsqlparser/statement/select/SelectTest.java

@@ -3982,4 +3982,18 @@ public void testWrongParseTreeIssue89() throws JSQLParserException {
                 .extracting(item -> item.toString())
                 .contains("col");
     }
+
+    @Test
+    public void testCaseWithComplexWhenExpression() throws JSQLParserException {
+        assertSqlCanBeParsedAndDeparsed("SELECT av.app_id, MAX(av.version_no) AS version_no\n"
+                + "FROM app_version av\n"
+                + "JOIN app_version_policy avp ON av.id = avp.app_version_id\n"
+                + "WHERE av.`status` = 1\n"
+                + "AND CASE \n"
+                + "WHEN avp.area IS NOT NULL\n"
+                + "AND length(avp.area) > 0 THEN avp.area LIKE CONCAT('%,', '12', ',%')\n"
+                + "OR avp.area LIKE CONCAT('%,', '13', ',%')\n"
+                + "ELSE 1 = 1\n"
+                + "END\n", true);
+    }
 }