Add JsonToPdxConverter interface specifying a contract to convert JSON to PDX.

The JSON may be expressed as a byte[] or a String.

Resolves gh-67.

spring-geode/src/test/java/org/springframework/geode/data/json/converter/JsonToPdxConverterUnitTests.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+package org.springframework.geode.data.json.converter;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.doCallRealMethod;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+
+import org.junit.Test;
+
+/**
+ * Unit Tests for {@link JsonToPdxConverter}
+ *
+ * @author John Blum
+ * @see org.junit.Test
+ * @see org.mockito.Mockito
+ * @see org.springframework.geode.data.json.converter.JsonToPdxConverter
+ * @since 1.3.0
+ */
+public class JsonToPdxConverterUnitTests {
+
+	@Test
+	public void convertByteArrayCallsConvertJsonString() {
+
+		JsonToPdxConverter converter = mock(JsonToPdxConverter.class);
+
+		doCallRealMethod().when(converter).convert(any(byte[].class));
+
+		String json = "{ \"name\": \"Jon Doe\"}";
+
+		converter.convert(json.getBytes());
+
+		verify(converter, times(1)).convert(eq(json));
+	}
+}