[generator] Use decl type's @deprecated-since if < member's (#1068)

Context: https://discord.com/channels/732297728826277939/732297837953679412/1052239604905934848

Imagine a type is deprecated in API-25 but its members were not
explicitly marked as deprecated:

	@deprecated
	public class TabActivity extends ActivityGroup {
	  public void setDefaultTab(String tag) { ... }
	}

Then in API-29 the member is explicitly marked as deprecated:

	@deprecated
	public class TabActivity extends ActivityGroup {
	  @deprecated
	  public void setDefaultTab(String tag) { ... }
	}

Due to the way `api-merge` calculates `@deprecated-since`, these
would end up with different values, with a resulting C# API:

	[ObsoletedOSPlatform("android25.0")]
	public class TabActivity : ActivityGroup
	{
	    [ObsoletedOSPlatform("android29.0")]
	    public void SetDefaultTab (string tag) { ... }
	}

While technically "fine", it is confusing that the method says it was
obsoleted in API-29 instead of API-25.

To fix this, if a member has a "higher" `@deprecated-since` value
than its declaring type, we set the member's `@deprecated-since`
value to the declaring type's `@deprecated-since` value.

tests/generator-Tests/Unit-Tests/CodeGeneratorTests.cs

@@ -576,7 +576,7 @@ public void ObsoletedOSPlatformAttributeUnneededSupport ()
 			    <class abstract='false' deprecated='not deprecated' final='false' name='Object' static='false' visibility='public' jni-signature='Ljava/lang/Object;' />
 			  </package>
 			  <package name='com.xamarin.android' jni-name='com/xamarin/android'>
-			    <class abstract='false' deprecated='This is a class deprecated since 19!' extends='java.lang.Object' extends-generic-aware='java.lang.Object' jni-extends='Ljava/lang/Object;' final='false' name='MyClass' static='false' visibility='public' jni-signature='Lcom/xamarin/android/MyClass;' deprecated-since='19'>
+			    <class abstract='false' deprecated='This is a class deprecated since 28!' extends='java.lang.Object' extends-generic-aware='java.lang.Object' jni-extends='Ljava/lang/Object;' final='false' name='MyClass' static='false' visibility='public' jni-signature='Lcom/xamarin/android/MyClass;' deprecated-since='28'>
 			      <field deprecated='This is a field deprecated since 0!' final='true' name='ACCEPT_HANDOVER' jni-signature='Ljava/lang/String;' static='true' transient='false' type='java.lang.String' type-generic-aware='java.lang.String' value='&quot;android.permission.ACCEPT_HANDOVER&quot;' visibility='public' volatile='false' deprecated-since='0'></field>
 			      <constructor deprecated='This is a constructor deprecated since empty string!' final='false' name='MyClass' jni-signature='()V' bridge='false' static='false' type='com.xamarin.android.MyClass' synthetic='false' visibility='public' deprecated-since=''></constructor>
 			      <method abstract='true' deprecated='deprecated' final='false' name='countAffectedRows' jni-signature='()I' bridge='false' native='false' return='int' jni-return='I' static='false' synchronized='false' synthetic='false' visibility='public' deprecated-since='25'></method>
@@ -599,7 +599,6 @@ public void ObsoletedOSPlatformAttributeUnneededSupport ()
 			generator.Context.ContextTypes.Pop ();
 
 			// These should use [Obsolete] because they have always been obsolete in all currently supported versions (21+)
-			Assert.True (writer.ToString ().Contains ("[global::System.Obsolete (@\"This is a class deprecated since 19!\")]"), writer.ToString ());
 			Assert.True (writer.ToString ().Contains ("[global::System.Obsolete (@\"This is a field deprecated since 0!\")]"), writer.ToString ());
 			Assert.True (writer.ToString ().Contains ("[global::System.Obsolete (@\"This is a constructor deprecated since empty string!\")]"), writer.ToString ());
 

tests/generator-Tests/Unit-Tests/XmlApiImporterTests.cs

@@ -78,6 +78,15 @@ public void CreateCtor_CorrectApiSinceFromClass ()
 			Assert.AreEqual (7, klass.Ctors [0].ApiAvailableSince);
 		}
 
+		[Test]
+		public void CreateCtor_CorrectDeprecatedSinceFromClass ()
+		{
+			var xml = XDocument.Parse ("<package name='com.example.test' jni-name='com/example/test'><class name='test' deprecated-since='7'><constructor name='ctor' deprecated-since='17' /></class></package>");
+			var klass = XmlApiImporter.CreateClass (xml.Root, xml.Root.Element ("class"), opt);
+
+			Assert.AreEqual (7, klass.Ctors [0].DeprecatedSince);
+		}
+
 		[Test]
 		public void CreateField_StudlyCaseName ()
 		{
@@ -138,6 +147,15 @@ public void CreateField_CorrectApiVersionFromClass ()
 			Assert.AreEqual (7, field.ApiAvailableSince);
 		}
 
+		[Test]
+		public void CreateField_CorrectDeprecatedSinceFromClass ()
+		{
+			var xml = XDocument.Parse ("<package name='com.example.test' jni-name='com/example/test'><class name='test' deprecated-since='7'><field name='$3' deprecated-since='17' /></class></package>");
+			var klass = XmlApiImporter.CreateClass (xml.Root, xml.Root.Element ("class"), opt);
+
+			Assert.AreEqual (7, klass.Fields [0].DeprecatedSince);
+		}
+
 		[Test]
 		public void CreateInterface_EnsureValidName ()
 		{
@@ -212,6 +230,15 @@ public void CreateMethod_CorrectApiSinceFromClass ()
 			Assert.AreEqual (7, klass.Methods [0].ApiAvailableSince);
 		}
 
+		[Test]
+		public void CreateMethod_CorrectDeprecatedSinceFromClass ()
+		{
+			var xml = XDocument.Parse ("<package name='com.example.test' jni-name='com/example/test'><class name='test' deprecated-since='7'><method name='-3' deprecated-since='17' /></class></package>");
+			var klass = XmlApiImporter.CreateClass (xml.Root, xml.Root.Element ("class"), opt);
+
+			Assert.AreEqual (7, klass.Methods [0].DeprecatedSince);
+		}
+
 		[Test]
 		public void CreateParameter_EnsureValidName ()
 		{

tools/generator/Java.Interop.Tools.Generator.Importers/XmlApiImporter.cs

@@ -191,6 +191,10 @@ public static Ctor CreateCtor (GenBase declaringType, XElement elem, CodeGenerat
 
 			ctor.Name = EnsureValidIdentifer (ctor.Name);
 
+			// If declaring type was deprecated earlier than member, use the type's deprecated-since
+			if (declaringType.DeprecatedSince.HasValue && declaringType.DeprecatedSince.Value < ctor.DeprecatedSince.GetValueOrDefault (0))
+				ctor.DeprecatedSince = declaringType.DeprecatedSince;
+
 			FillApiSince (ctor, elem);
 
 			return ctor;
@@ -230,6 +234,10 @@ public static Field CreateField (GenBase declaringType, XElement elem, CodeGener
 				field.Name = EnsureValidIdentifer (field.Name);
 			}
 
+			// If declaring type was deprecated earlier than member, use the type's deprecated-since
+			if (declaringType.DeprecatedSince.HasValue && declaringType.DeprecatedSince.Value < field.DeprecatedSince.GetValueOrDefault (0))
+				field.DeprecatedSince = declaringType.DeprecatedSince;
+
 			FillApiSince (field, elem);
 			SetLineInfo (field, elem, options);
 
@@ -398,6 +406,10 @@ public static Method CreateMethod (GenBase declaringType, XElement elem, CodeGen
 
 			method.FillReturnType ();
 
+			// If declaring type was deprecated earlier than member, use the type's deprecated-since
+			if (declaringType.DeprecatedSince.HasValue && declaringType.DeprecatedSince.Value < method.DeprecatedSince.GetValueOrDefault (0))
+				method.DeprecatedSince = declaringType.DeprecatedSince;
+
 			FillApiSince (method, elem);
 			SetLineInfo (method, elem, options);