Unify ProtobufJsonReader and ProtobufJsonWriter implementations into single classes.

Motivation:

- Simplify the codebase by eliminating separate `Impl` classes that provide no additional value.
- Improve clarity by making `ProtobufJsonReader` and `ProtobufJsonWriter` self-contained.

Changes:

- Merged `ProtobufJsonReaderImpl` into `ProtobufJsonReader`.
- Merged `ProtobufJsonWriterImpl` into `ProtobufJsonWriter`.
- Updated constructors to handle `JsonWireFormat` directly within unified classes.
- Removed redundant `Impl` classes and adjusted usage across the codebase.

Author: zZHorizonZz

vertx-grpc-common/src/main/java/io/vertx/grpc/common/impl/ProtobufJsonReader.java

@@ -1,23 +1,37 @@
 package io.vertx.grpc.common.impl;
 
+import com.google.protobuf.InvalidProtocolBufferException;
 import com.google.protobuf.Message;
+import com.google.protobuf.util.JsonFormat;
 import io.vertx.core.buffer.Buffer;
 import io.vertx.grpc.common.CodecException;
 import io.vertx.grpc.common.JsonWireFormat;
 
+import java.nio.charset.StandardCharsets;
+
 /**
  * Reads JSON {@link Buffer} payloads into a protobuf {@link Message.Builder}.
  * <p>
- * Use {@link #create(JsonWireFormat)} to get an instance. The default implementation is backed
- * by {@code com.google.protobuf.util.JsonFormat}.
+ * Use {@link #create(JsonWireFormat)} to get an instance, backed by
+ * {@code com.google.protobuf.util.JsonFormat}.
  */
-public interface ProtobufJsonReader {
+public final class ProtobufJsonReader {
 
   /**
    * @return a reader configured from {@code format}
    */
-  static ProtobufJsonReader create(JsonWireFormat format) {
-    return new ProtobufJsonReaderImpl(format);
+  public static ProtobufJsonReader create(JsonWireFormat format) {
+    return new ProtobufJsonReader(format);
+  }
+
+  private final JsonFormat.Parser parser;
+
+  private ProtobufJsonReader(JsonWireFormat format) {
+    JsonFormat.Parser parser = JsonFormat.parser();
+    if (format.ignoringUnknownFields()) {
+      parser = parser.ignoringUnknownFields();
+    }
+    this.parser = parser;
   }
 
   /**
@@ -27,5 +41,11 @@ static ProtobufJsonReader create(JsonWireFormat format) {
    * @param builder the target builder
    * @throws CodecException when the payload cannot be parsed
    */
-  void merge(Buffer payload, Message.Builder builder) throws CodecException;
+  public void merge(Buffer payload, Message.Builder builder) throws CodecException {
+    try {
+      parser.merge(payload.toString(StandardCharsets.UTF_8), builder);
+    } catch (InvalidProtocolBufferException e) {
+      throw new CodecException(e);
+    }
+  }
 }

vertx-grpc-common/src/main/java/io/vertx/grpc/common/impl/ProtobufJsonReaderImpl.java

@@ -1,23 +1,47 @@
 package io.vertx.grpc.common.impl;
 
+import com.google.protobuf.InvalidProtocolBufferException;
 import com.google.protobuf.MessageOrBuilder;
+import com.google.protobuf.util.JsonFormat;
 import io.vertx.core.buffer.Buffer;
 import io.vertx.grpc.common.CodecException;
 import io.vertx.grpc.common.JsonWireFormat;
 
 /**
  * Writes a protobuf {@link MessageOrBuilder} as a JSON {@link Buffer}.
  * <p>
- * Use {@link #create(JsonWireFormat)} to get an instance. The default implementation is backed
- * by {@code com.google.protobuf.util.JsonFormat}.
+ * Use {@link #create(JsonWireFormat)} to get an instance, backed by
+ * {@code com.google.protobuf.util.JsonFormat}.
  */
-public interface ProtobufJsonWriter {
+public final class ProtobufJsonWriter {
 
   /**
    * @return a writer configured from {@code format}
    */
-  static ProtobufJsonWriter create(JsonWireFormat format) {
-    return new ProtobufJsonWriterImpl(format);
+  public static ProtobufJsonWriter create(JsonWireFormat format) {
+    return new ProtobufJsonWriter(format);
+  }
+
+  private final JsonFormat.Printer printer;
+
+  private ProtobufJsonWriter(JsonWireFormat format) {
+    JsonFormat.Printer printer = JsonFormat.printer();
+    if (format.alwaysPrintFieldsWithNoPresence()) {
+      printer = printer.alwaysPrintFieldsWithNoPresence();
+    }
+    if (format.omittingInsignificantWhitespace()) {
+      printer = printer.omittingInsignificantWhitespace();
+    }
+    if (format.preservingProtoFieldNames()) {
+      printer = printer.preservingProtoFieldNames();
+    }
+    if (format.printingEnumsAsInts()) {
+      printer = printer.printingEnumsAsInts();
+    }
+    if (format.sortingMapKeys()) {
+      printer = printer.sortingMapKeys();
+    }
+    this.printer = printer;
   }
 
   /**
@@ -27,5 +51,11 @@ static ProtobufJsonWriter create(JsonWireFormat format) {
    * @return the encoded JSON payload
    * @throws CodecException when the message cannot be encoded
    */
-  Buffer write(MessageOrBuilder message) throws CodecException;
+  public Buffer write(MessageOrBuilder message) throws CodecException {
+    try {
+      return Buffer.buffer(printer.print(message));
+    } catch (InvalidProtocolBufferException e) {
+      throw new CodecException(e);
+    }
+  }
 }