Fix, when case of multiple non-default public constructors use the largest constructor

Author: rbygrave

blackbox-test/src/main/java/org/example/customer/SomeAddressWrapper.java

@@ -1,8 +1,17 @@
 package org.example.customer;
 
 import io.avaje.jsonb.Json;
+
+import java.util.Collections;
 import java.util.List;
 
 @Json
-public record SomeAddressWrapper (Long id, Address address, List<String> tags) {
+public record SomeAddressWrapper(Long id, Address address, List<String> tags) {
+
+  /**
+   * Additional constructor.
+   */
+  public SomeAddressWrapper(long id, Address address) {
+    this(id, address, Collections.emptyList());
+  }
 }

blackbox-test/src/test/java/org/example/customer/SomeAddressWrapperTest.java

@@ -18,10 +18,10 @@ class SomeAddressWrapperTest {
   void test_when_null() {
 
     var type = jsonb.type(SomeAddressWrapper.class);
-    String asJson = type.toJson(new SomeAddressWrapper(43L, null, Collections.emptyList()));
-    assertThat(asJson).isEqualTo("{\"id\":43}");
+    String asJson = type.toJson(new SomeAddressWrapper(43L, null, List.of("a", "b")));
+    assertThat(asJson).isEqualTo("{\"id\":43,\"tags\":[\"a\",\"b\"]}");
 
-    var myList = List.of( new SomeAddressWrapper(43L, null, Collections.emptyList()),  new SomeAddressWrapper(44L, null, Collections.emptyList()));
+    var myList = List.of( new SomeAddressWrapper(43L, null),  new SomeAddressWrapper(44L, null));
 
     String asJsonList = type.list().toJson(myList);
     assertThat(asJsonList).isEqualTo("[{\"id\":43},{\"id\":44}]");
@@ -59,7 +59,7 @@ void includeEmpty_viaJsonB() {
     Jsonb jsonb = Jsonb.newBuilder().serializeEmpty(true).build();
 
     var type = jsonb.type(SomeAddressWrapper.class);
-    String asJson = type.toJson(new SomeAddressWrapper(43L, null, Collections.emptyList()));
+    String asJson = type.toJson(new SomeAddressWrapper(43L, null));
     assertThat(asJson).isEqualTo("{\"id\":43,\"tags\":[]}");
   }
 
@@ -70,7 +70,7 @@ void includeNullAndEmpty_viaJsonB() {
     Jsonb jsonb = Jsonb.newBuilder().serializeNulls(true).serializeEmpty(true).build();
 
     var type = jsonb.type(SomeAddressWrapper.class);
-    String asJson = type.toJson(new SomeAddressWrapper(43L, null, Collections.emptyList()));
+    String asJson = type.toJson(new SomeAddressWrapper(43L, null));
     assertThat(asJson).isEqualTo("{\"id\":43,\"address\":null,\"tags\":[]}");
   }
 }

jsonb-generator/src/main/java/io/avaje/jsonb/generator/TypeReader.java

@@ -264,7 +264,20 @@ private MethodReader determineConstructor() {
       // fallback to the single public constructor
       return allPublic.get(0);
     }
-    return null;
+    // find the largest constructor
+    int argCount = 0;
+    MethodReader largestConstructor = null;
+    for (MethodReader ctor : publicConstructors) {
+      if (ctor.isPublic()) {
+        int paramCount = ctor.getParams().size();
+        if (paramCount > argCount) {
+          largestConstructor = ctor;
+          argCount = paramCount;
+        }
+      }
+    }
+
+    return largestConstructor;
   }
 
   void process() {