fix: add int and string management on %json_add

That fixes:
- https://github.com/plantuml/plantuml/issues/328#issuecomment-2071079413

Here is a fix for `int` and `string`, in order to manage:

```puml
%json_add({"age" : 30}, name, 123) '=> {"age":30,"name":123}
```

```puml
%json_add({"age" : 30}, name, Sally) '=> {"age":30,"name":"Sally"}
```

[FYI @philCryoport]
Reagrds,
Th.

src/net/sourceforge/plantuml/tim/expression/TValue.java

@@ -36,6 +36,7 @@ package net.sourceforge.plantuml.tim.expression;
 
 import java.util.Objects;
 
+import net.sourceforge.plantuml.json.Json;
 import net.sourceforge.plantuml.json.JsonValue;
 
 public final class TValue {
@@ -221,4 +222,13 @@ public final class TValue {
 		return jsonValue;
 	}
 
+	public JsonValue toJsonValue() {
+		if (isNumber()) {
+			return Json.value(this.intValue);
+		}
+		if (isString()) {
+			return Json.value(this.stringValue);
+		}
+		return this.jsonValue;
+	}
 }

src/net/sourceforge/plantuml/tim/stdlib/JsonAdd.java

@@ -72,17 +72,15 @@ public class JsonAdd extends SimpleReturnFunction {
 		if (!json.isArray() && !json.isObject())
 			return data;
 		if (json.isArray()) {
-			final JsonValue value = values.get(1).toJson();
+			final JsonValue value = values.get(1).toJsonValue();
-			final JsonArray array = (JsonArray) json;
+			json.asArray().add(value);
-			array.add(value);
+			return TValue.fromJson(json);
-			return TValue.fromJson(array);
 		}
 		if (json.isObject()) {
 			final String name = values.get(1).toString();
-			final JsonValue value = values.get(2).toJson();
+			final JsonValue value = values.get(2).toJsonValue();
-			final JsonObject object = (JsonObject) json;
+			json.asObject().add(name, value);
-			object.add(name, value);
+			return TValue.fromJson(json);
-			return TValue.fromJson(object);
 		}
 		throw new EaterException("Bad JSON type", location);
 	}

test/net/sourceforge/plantuml/tim/TimTestUtils.java

@@ -83,4 +83,18 @@ public class TimTestUtils {
 		assertEquals(expected, tValue.toString());
 	}
 
+	// Tfunc: (JsonValue, String, String) -> (String)
+	public static void assertTimExpectedOutputFromInput(TFunction func, JsonValue input1,  String input2, String input3, String expected) throws EaterException {
+		final List<TValue> values = Arrays.asList(TValue.fromJson(input1), TValue.fromString(input2), TValue.fromString(input3));
+		final TValue tValue = func.executeReturnFunction(null, null, null, values, null);
+		assertEquals(expected, tValue.toString());
+	}
+
+	// Tfunc: (JsonValue, String, Int) -> (String)
+	public static void assertTimExpectedOutputFromInput(TFunction func, JsonValue input1,  String input2, Integer input3, String expected) throws EaterException {
+		final List<TValue> values = Arrays.asList(TValue.fromJson(input1), TValue.fromString(input2), TValue.fromInt(input3));
+		final TValue tValue = func.executeReturnFunction(null, null, null, values, null);
+		assertEquals(expected, tValue.toString());
+	}
+
 }

test/net/sourceforge/plantuml/tim/stdlib/JsonAddTest.java

@@ -38,7 +38,35 @@ class JsonAddTest {
 	void Test_with_Array_Json(@ConvertWith(StringJsonConverter.class) JsonValue input1, @ConvertWith(StringJsonConverter.class) JsonValue input2, String expected) throws EaterException {
 		assertTimExpectedOutputFromInput(cut, input1, input2, expected);
 	}
-	
+
+	@ParameterizedTest(name = paramTestName)
+	@CsvSource(value = {
+			"  [],                -1,        '[\"-1\"]' ",
+			"  [],                1,         '[\"1\"]' ",
+			"  [0],               123,       '[0,\"123\"]' ",
+			"  [0],               a,         '[0,\"a\"]' ",
+			"  [0],               \"a\",     '[0,\"\\\"a\\\"\"]' ",
+			"  [0],               a b c,     '[0,\"a b c\"]' ",
+			"  [0],               \"a b c\", '[0,\"\\\"a b c\\\"\"]' ",
+			" '[{\"a\":[1, 2]}]', 1,         '[{\"a\":[1,2]},\"1\"]' ",
+			" '[{\"a\":[1, 2]}]', a,         '[{\"a\":[1,2]},\"a\"]' ",
+	})
+	void Test_with_Array_Json_add_Str(@ConvertWith(StringJsonConverter.class) JsonValue input1, String input2, String expected) throws EaterException {
+		assertTimExpectedOutputFromInput(cut, input1, input2, expected);
+	}
+
+	@ParameterizedTest(name = paramTestName)
+	@CsvSource(value = {
+			"  [],                -1,   [-1]",
+			"  [],                1,    [1]",
+			"  [0],               123, '[0,123]' ",
+			" '[{\"a\":[1, 2]}]', 1,   '[{\"a\":[1,2]},1]' ",
+			" '[{\"a\":[1, 2]}]', 123, '[{\"a\":[1,2]},123]' ",
+	})
+	void Test_with_Array_Json_add_Int(@ConvertWith(StringJsonConverter.class) JsonValue input1, Integer input2, String expected) throws EaterException {
+		assertTimExpectedOutputFromInput(cut, input1, input2, expected);
+	}
+
 	@ParameterizedTest(name = "[{index}] " + cutName + "({0}, {1}, {2}) = {3}")
 	@CsvSource(value = {
 			" {}, a, 1,  {\"a\":1}",
@@ -57,6 +85,27 @@ class JsonAddTest {
 		assertTimExpectedOutputFromInput(cut, input1, input2, input3, expected);
 	}
 
+	@ParameterizedTest(name = "[{index}] " + cutName + "({0}, {1}, {2}) = {3}")
+	@CsvSource(value = {
+			" {}, a, 1,         {\"a\":\"1\"}",
+			" {}, a, 'abc',    '{\"a\":\"abc\"}'",
+			" {}, a, 'a b c',  '{\"a\":\"a b c\"}'",
+			" {\"age\" : 30}, name, Sally, '{\"age\":30,\"name\":\"Sally\"}'",
+	})
+	void Test_with_Object_Json_add_Str(@ConvertWith(StringJsonConverter.class) JsonValue input1, String input2, String input3, String expected) throws EaterException {
+		assertTimExpectedOutputFromInput(cut, input1, input2, input3, expected);
+	}
+
+	@ParameterizedTest(name = "[{index}] " + cutName + "({0}, {1}, {2}) = {3}")
+	@CsvSource(value = {
+			" {}, a, 1,    {\"a\":1}",
+			" {}, a, 123, '{\"a\":123}'",
+			" {\"age\" : 30}, name, 123,  '{\"age\":30,\"name\":123}'",
+	})
+	void Test_with_Object_Json_add_Int(@ConvertWith(StringJsonConverter.class) JsonValue input1, String input2, Integer input3, String expected) throws EaterException {
+		assertTimExpectedOutputFromInput(cut, input1, input2, input3, expected);
+	}
+
 	@Nested
 	class Not_Nominal_Test {
 		@ParameterizedTest(name = paramTestName)