CAY-2915 CayenneModeler DB Import forces meaningful PK

 - treat empty string as an `exclude all`, not `include all`

Author: stariy95

cayenne-dbsync/src/main/java/org/apache/cayenne/dbsync/reverse/dbimport/DbImportConfiguration.java

@@ -19,6 +19,8 @@
 package org.apache.cayenne.dbsync.reverse.dbimport;
 
 import java.io.File;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.regex.Pattern;
 
 import org.apache.cayenne.CayenneRuntimeException;
@@ -166,18 +168,24 @@ public void setCayenneProject(File cayenneProject) {
 
     public NameFilter createMeaningfulPKFilter() {
 
-        if (meaningfulPkTables == null) {
+        if (meaningfulPkTables == null || meaningfulPkTables.trim().isEmpty()) {
             return NamePatternMatcher.EXCLUDE_ALL;
         }
 
         // TODO: this filter can't handle table names with comma in them
         String[] patternStrings = meaningfulPkTables.split(",");
-        Pattern[] patterns = new Pattern[patternStrings.length];
-        for (int i = 0; i < patterns.length; i++) {
-            patterns[i] = Pattern.compile(patternStrings[i]);
+        List<Pattern> patterns = new ArrayList<>(patternStrings.length);
+        for (String patternString : patternStrings) {
+            if (!patternString.trim().isEmpty()) {
+                patterns.add(Pattern.compile(patternString));
+            }
+        }
+
+        if (patterns.isEmpty()) {
+            return NamePatternMatcher.EXCLUDE_ALL;
         }
 
-        return new NamePatternMatcher(patterns, new Pattern[0]);
+        return new NamePatternMatcher(patterns.toArray(new Pattern[0]), new Pattern[0]);
     }
 
     public ObjectNameGenerator createNameGenerator() {
@@ -201,7 +209,7 @@ public ObjectNameGenerator createNameGenerator() {
     }
 
     protected DbEntityNameStemmer createStemmer() {
-        return (stripFromTableNames == null || stripFromTableNames.length() == 0)
+        return (stripFromTableNames == null || stripFromTableNames.isEmpty())
                 ? NoStemStemmer.getInstance()
                 : new PatternStemmer(stripFromTableNames, false);
     }

cayenne-dbsync/src/test/java/org/apache/cayenne/dbsync/reverse/dbimport/DbImportConfigurationTest.java

@@ -0,0 +1,71 @@
+/*****************************************************************
+ *   Licensed to the Apache Software Foundation (ASF) under one
+ *  or more contributor license agreements.  See the NOTICE file
+ *  distributed with this work for additional information
+ *  regarding copyright ownership.  The ASF licenses this file
+ *  to you under the Apache License, Version 2.0 (the
+ *  "License"); you may not use this file except in compliance
+ *  with the License.  You may obtain a copy of the License at
+ *
+ *    https://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing,
+ *  software distributed under the License is distributed on an
+ *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ *  KIND, either express or implied.  See the License for the
+ *  specific language governing permissions and limitations
+ *  under the License.
+ ****************************************************************/
+
+package org.apache.cayenne.dbsync.reverse.dbimport;
+
+import org.apache.cayenne.dbsync.filter.NameFilter;
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+public class DbImportConfigurationTest {
+
+    @Test
+    public void testCreateMeaningfulPKFilter_NullExcludesAll() {
+        DbImportConfiguration config = new DbImportConfiguration();
+        config.setMeaningfulPkTables(null);
+        NameFilter filter = config.createMeaningfulPKFilter();
+
+        assertFalse(filter.isIncluded("ARTIST"));
+        assertFalse(filter.isIncluded("PAINTING"));
+        assertFalse(filter.isIncluded("ANY_TABLE"));
+    }
+
+    @Test
+    public void testCreateMeaningfulPKFilter_EmptyStringExcludesAll() {
+        DbImportConfiguration config = new DbImportConfiguration();
+        config.setMeaningfulPkTables("");
+        NameFilter filter = config.createMeaningfulPKFilter();
+
+        assertFalse(filter.isIncluded("ARTIST"));
+        assertFalse(filter.isIncluded("ANY_TABLE"));
+    }
+
+    @Test
+    public void testCreateMeaningfulPKFilter_WhitespaceStringExcludesAll() {
+        DbImportConfiguration config = new DbImportConfiguration();
+        config.setMeaningfulPkTables("   ");
+        NameFilter filter = config.createMeaningfulPKFilter();
+
+        assertFalse(filter.isIncluded("ARTIST"));
+        assertFalse(filter.isIncluded("ANY_TABLE"));
+    }
+
+    @Test
+    public void testCreateMeaningfulPKFilter_CommaSeparatedPatterns() {
+        DbImportConfiguration config = new DbImportConfiguration();
+        config.setMeaningfulPkTables("^ART.*$,,^T1$"); // Note double comma
+        NameFilter filter = config.createMeaningfulPKFilter();
+
+        assertTrue(filter.isIncluded("ARTIST"));
+        assertTrue(filter.isIncluded("T1"));
+
+        assertFalse("Empty tokens should not match everything", filter.isIncluded("PAINTING"));
+    }
+}

modeler/cayenne-modeler/src/main/java/org/apache/cayenne/modeler/editor/dbimport/DbImportView.java

@@ -250,8 +250,7 @@ public boolean isUseJava7Typed() {
     }
 
     public String getMeaningfulPk() {
-        return "".equals(configPanel.getMeaningfulPk().getComponent().getText())
-                ? null : configPanel.getMeaningfulPk().getComponent().getText();
+        return configPanel.getMeaningfulPk().getComponent().getText();
     }
 
     public String getNamingStrategy() {