Add Graal native-image build in bitcoinj-cli

The executable doesn’t run correctly due to an apparent
bug in Graal, but the build seems to work.

bitcoinj-cli/build.gradle

@@ -35,6 +35,23 @@ shadowJar {
     classifier = ''
 }
 
+// Compile a native image using Graal's native-image tool
+// Graal must be installed at $GRAAL_HOME
+task graalNativeImage(type:Exec, dependsOn: jar) {
+    workingDir = projectDir
+    executable = "${System.env.GRAAL_HOME}/bin/native-image"
+    args = [ '--verbose',
+             '-cp', configurations.runtime.asPath,
+             '-jar', jar.archivePath,
+             '-H:Path=build',
+             '-H:Name=cj-bitcoin-cli',
+             '-H:ReflectionConfigurationFiles=graal-reflection-config.json',
+             '-H:EnableURLProtocols=http',
+             '-H:+ReportUnsupportedElementsAtRuntime'
+    ]
+}
+
+
 // Test Structure
 sourceSets {
     integrationTest {

bitcoinj-cli/graal-reflection-config.json

@@ -0,0 +1,17 @@
+[
+  {
+    "name" : "org.consensusj.jsonrpc.JsonRpcRequest",
+    "allDeclaredMethods" : true,
+    "allPublicMethods" : true
+  },
+  {
+    "name" : "java.lang.Object",
+    "allDeclaredMethods" : true,
+    "allPublicMethods" : true
+  },
+  {
+    "name" : "java.util.List",
+    "allDeclaredMethods" : true,
+    "allPublicMethods" : true
+  }
+]