Fix #5246: allow properties-based Constructor auto-detection with 0-params Constructor

src/main/java/tools/jackson/databind/introspect/POJOPropertiesCollector.java

@@ -719,8 +719,9 @@ protected void _addCreators(Map<String, POJOPropertyBuilder> props)
                 && !ctorDetector.requireCtorAnnotation()) {
             // But only if no Default (0-params) constructor available OR if we are configured
             // to prefer properties-based Creators
-            if ((_classDef.getDefaultConstructor() == null)
-                    || ctorDetector.singleArgCreatorDefaultsToProperties()) {
+            // 09-Sep-2025, tatu: [databind#5045] Actually let's allow implicit even in
+            //   case of also having 0-param constructor (un-annotated at this point)
+            if ((zeroParamsConstructor == null) || !zeroParamsConstructor.isAnnotated()) {
                 _addImplicitConstructor(creators, constructors, props);
             }
         }

src/test/java/tools/jackson/databind/deser/creators/NoParamsCreator5246Test.java

@@ -0,0 +1,36 @@
+package tools.jackson.databind.deser.creators;
+
+import tools.jackson.databind.*;
+import tools.jackson.databind.testutil.DatabindTestUtil;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class NoParamsCreator5246Test extends DatabindTestUtil
+{
+    static class Pojo5246 {
+         final int productId;
+         final String name;
+
+         public Pojo5246() {
+              this(0, null);
+         }
+
+         public Pojo5246(int productId, String name) {
+              this.productId = productId;
+              this.name = name;
+         }
+    }
+
+    // For [databind#5246]
+    @Test
+    void testNoParamsCreator() throws Exception {
+        ObjectMapper mapper = jsonMapperBuilder()
+                .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, true)
+                .build();
+        Pojo5246 pojo = mapper.readValue("{\"productId\":1,\"name\":\"foo\"}", Pojo5246.class);
+        assertEquals(1, pojo.productId);
+        assertEquals("foo", pojo.name);
+    }
+}

src/test/java/tools/jackson/databind/deser/creators/TestConstructFromMap.java

@@ -54,7 +54,7 @@ static FactoryFromPoint createIt(Point p)
     // Also: let's test BigDecimal-from-JSON-String factory
     static class FactoryFromDecimalString
     {
-	int _value;
+        int _value;
 
         private FactoryFromDecimalString(BigDecimal d) {
 	    _value = d.intValue();