Encapsulate all used java classes

Summary:
@public

Moves all Java classes used from C++ to their own header + implementation file. In `YGJNI.cpp`, we only call methods on these objects deriving from `jni::JavaClass`.

This is only a bit of cleanup, no functional change.

Reviewed By: SidharthGuglani

Differential Revision: D14261043

fbshipit-source-id: 2db1d81cb7f56a4cdc24b182b2166e1d7e24ba3c

java/jni/YGJTypes.h

@@ -0,0 +1,42 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the LICENSE
+ * file in the root directory of this source tree.
+ */
+#include <fb/fbjni.h>
+#include <yoga/YGValue.h>
+
+struct JYogaNode : public facebook::jni::JavaClass<JYogaNode> {
+  static constexpr auto kJavaDescriptor = "Lcom/facebook/yoga/YogaNodeJNI;";
+
+  jfloat baseline(jfloat width, jfloat height);
+  jlong measure(jfloat width, jint widthMode, jfloat height, jint heightMode);
+};
+
+struct JYogaConfig : public facebook::jni::JavaClass<JYogaConfig> {
+  static constexpr auto kJavaDescriptor = "Lcom/facebook/yoga/YogaConfig;";
+};
+
+struct JYogaLogLevel : public facebook::jni::JavaClass<JYogaLogLevel> {
+  static constexpr auto kJavaDescriptor = "Lcom/facebook/yoga/YogaLogLevel;";
+
+  static facebook::jni::local_ref<JYogaLogLevel> fromInt(jint);
+};
+
+struct JYogaLogger : public facebook::jni::JavaClass<JYogaLogger> {
+  static constexpr auto kJavaDescriptor = "Lcom/facebook/yoga/YogaLogger";
+
+  void log(
+      facebook::jni::alias_ref<JYogaNode>,
+      facebook::jni::alias_ref<JYogaLogLevel>,
+      jstring);
+};
+
+struct JYogaValue : public facebook::jni::JavaClass<JYogaValue> {
+  constexpr static auto kJavaDescriptor = "Lcom/facebook/yoga/YogaValue;";
+
+  static facebook::jni::local_ref<javaobject> create(YGValue value) {
+    return newInstance(value.value, static_cast<int>(value.unit));
+  }
+};