Preserve http2 option when going from javadsl to scaladsl

akka-http-core/src/main/mima-filters/10.1.3.backwards.excludes

@@ -10,3 +10,9 @@ ProblemFilters.exclude[IncompatibleResultTypeProblem]("akka.http.scaladsl.settin
 ProblemFilters.exclude[DirectMissingMethodProblem]("akka.http.scaladsl.settings.Http2ServerSettings#Http2ServerSettingsImpl.apply")
 ProblemFilters.exclude[DirectMissingMethodProblem]("akka.http.scaladsl.settings.Http2ServerSettings#Http2ServerSettingsImpl.copy")
 ProblemFilters.exclude[DirectMissingMethodProblem]("akka.http.scaladsl.settings.Http2ServerSettings#Http2ServerSettingsImpl.this")
+
+# #2149: additions to @DoNotInherit classes
+
+ProblemFilters.exclude[ReversedMissingMethodProblem]("akka.http.javadsl.HttpsConnectionContext.withHttp2")
+ProblemFilters.exclude[ReversedMissingMethodProblem]("akka.http.javadsl.HttpConnectionContext.withHttp2")
+ProblemFilters.exclude[ReversedMissingMethodProblem]("akka.http.javadsl.ConnectionContext.withHttp2")

akka-http-core/src/main/scala/akka/http/javadsl/ConnectHttp.scala

@@ -7,6 +7,8 @@ package akka.http.javadsl
 import java.util.Locale
 import java.util.Optional
 
+import scala.compat.java8.OptionConverters._
+
 import akka.annotation.{ DoNotInherit, InternalApi }
 import akka.http.javadsl.model.Uri
 import akka.http.scaladsl.UseHttp2.Negotiated
@@ -21,11 +23,14 @@ abstract class ConnectHttp {
   def http2: UseHttp2
 
   final def effectiveHttpsConnectionContext(fallbackContext: HttpsConnectionContext): HttpsConnectionContext =
-    connectionContext.orElse(fallbackContext)
+    connectionContext.asScala
+      .getOrElse(fallbackContext)
+      .withHttp2(http2)
 
   final def effectiveConnectionContext(fallbackContext: ConnectionContext): ConnectionContext =
-    if (connectionContext.isPresent) connectionContext.get()
-    else fallbackContext
+    connectionContext.asScala // Optional doesn't deal well with covariance
+      .getOrElse(fallbackContext)
+      .withHttp2(http2)
 
   override def toString = s"ConnectHttp($host,$port,$isHttps,$connectionContext,$http2)"
 }

akka-http-core/src/main/scala/akka/http/javadsl/ConnectionContext.scala

@@ -65,6 +65,8 @@ abstract class ConnectionContext {
   def sslConfig: Option[AkkaSSLConfig]
   def http2: UseHttp2
 
+  def withHttp2(newValue: UseHttp2): ConnectionContext
+
   @deprecated("'default-http-port' and 'default-https-port' configuration properties are used instead", since = "10.0.11")
   def getDefaultPort: Int
 }
@@ -74,13 +76,17 @@ abstract class HttpConnectionContext(override val http2: UseHttp2) extends akka.
   override final def isSecure = false
   override final def getDefaultPort = 80
   override def sslConfig: Option[AkkaSSLConfig] = None
+
+  override def withHttp2(newValue: UseHttp2): HttpConnectionContext
 }
 
 @DoNotInherit
 abstract class HttpsConnectionContext(override val http2: UseHttp2) extends akka.http.javadsl.ConnectionContext {
   override final def isSecure = true
   override final def getDefaultPort = 443
 
+  override def withHttp2(newValue: UseHttp2): HttpsConnectionContext
+
   /** Java API */
   def getEnabledCipherSuites: Optional[JCollection[String]]
   /** Java API */

akka-http-core/src/main/scala/akka/http/scaladsl/ConnectionContext.scala

@@ -11,6 +11,7 @@ import com.typesafe.sslconfig.akka.AkkaSSLConfig
 import scala.collection.JavaConverters._
 import java.util.{ Optional, Collection ⇒ JCollection }
 
+import akka.http.javadsl
 import akka.http.scaladsl.UseHttp2.Negotiated
 import javax.net.ssl._
 
@@ -93,11 +94,22 @@ final class HttpsConnectionContext(
   override def getEnabledProtocols: Optional[JCollection[String]] = enabledProtocols.map(_.asJavaCollection).asJava
   override def getClientAuth: Optional[TLSClientAuth] = clientAuth.asJava
   override def getSslParameters: Optional[SSLParameters] = sslParameters.asJava
+
+  override def withHttp2(newValue: javadsl.UseHttp2): javadsl.HttpsConnectionContext =
+    withHttp2(newValue.asScala)
+  def withHttp2(newValue: UseHttp2): javadsl.HttpsConnectionContext =
+    new HttpsConnectionContext(sslContext, sslConfig, enabledCipherSuites, enabledProtocols, clientAuth, sslParameters, newValue)
 }
 
 sealed class HttpConnectionContext(http2: UseHttp2) extends akka.http.javadsl.HttpConnectionContext(http2) with ConnectionContext {
   def this() = this(Negotiated)
+
+  override def withHttp2(newValue: javadsl.UseHttp2): javadsl.HttpConnectionContext =
+    withHttp2(newValue.asScala)
+  def withHttp2(newValue: UseHttp2): javadsl.HttpConnectionContext =
+    new HttpConnectionContext(newValue)
 }
+
 final object HttpConnectionContext extends HttpConnectionContext(Negotiated) {
   /** Java API */
   def getInstance() = this

akka-http-core/src/test/scala/akka/http/javadsl/ConnectHttpSpec.scala

@@ -99,5 +99,14 @@ class ConnectHttpSpec extends WordSpec with Matchers with BeforeAndAfterAll {
       }
       ex.getMessage should include("non https scheme!")
     }
+    "connect toHost HTTP/2 only" in {
+      val connect = ConnectHttp.toHost("http://127.0.0.1", 8080, UseHttp2.always)
+      connect.effectiveConnectionContext(httpsContext).http2 should equal(UseHttp2.always)
+    }
+    "connect toHostHttps HTTP/2 only" in {
+      val connect = ConnectHttp.toHostHttps("https://127.0.0.1", 8080, UseHttp2.always)
+      connect.effectiveConnectionContext(httpsContext).http2 should equal(UseHttp2.always)
+    }
+
   }
 }