[FLINK-8186] Exclude flink-avro from flink-dist; fix AvroUtils loading

Before, AvroUtils were loaded when the class was loaded which didn't
take into account the user-code ClassLoader. Now, we try loading avro
utils with the Thread context ClassLoader.

flink-core/src/main/java/org/apache/flink/api/java/typeutils/AvroUtils.java

@@ -37,12 +37,14 @@ public abstract class AvroUtils {
 
  private static final String AVRO_KRYO_UTILS = "org.apache.flink.formats.avro.utils.AvroKryoSerializerUtils";
 
- private static final AvroUtils INSTANCE = loadAvroKryoUtils();
-
- private static AvroUtils loadAvroKryoUtils() {
+ /**
+ * Returns either the default {@link AvroUtils} which throw an exception in cases where Avro
+ * would be needed or loads the specific utils for Avro from flink-avro.
+ */
+ public static AvroUtils getAvroUtils() {
  // try and load the special AvroUtils from the flink-avro package
  try {
- Class<?> clazz = Class.forName(AVRO_KRYO_UTILS, false, AvroUtils.class.getClassLoader());
+ Class<?> clazz = Class.forName(AVRO_KRYO_UTILS, false, Thread.currentThread().getContextClassLoader());
  return clazz.asSubclass(AvroUtils.class).getConstructor().newInstance();
  } catch (ClassNotFoundException e) {
  // cannot find the utils, return the default implementation
@@ -52,14 +54,6 @@ private static AvroUtils loadAvroKryoUtils() {
  }
  }
 
- /**
- * Returns either the default {@link AvroUtils} which throw an exception in cases where Avro
- * would be needed or loads the specific utils for Avro from flink-avro.
- */
- public static AvroUtils getAvroUtils() {
- return INSTANCE;
- }
-
  // ------------------------------------------------------------------------
 
  /**

flink-dist/pom.xml

@@ -79,12 +79,6 @@ under the License.
  <version>${project.version}</version>
  </dependency>
 
- <dependency>
- <groupId>org.apache.flink</groupId>
- <artifactId>flink-avro</artifactId>
- <version>${project.version}</version>
- </dependency>
-
  <dependency>
  <groupId>org.apache.flink</groupId>
  <artifactId>flink-streaming-java_${scala.binary.version}</artifactId>
@@ -492,10 +486,6 @@ under the License.
  </excludes>
  </artifactSet>
  <relocations>
- <relocation>
- <pattern>org.codehaus.jackson</pattern>
- <shadedPattern>org.apache.flink.formats.avro.shaded.org.codehaus.jackson</shadedPattern>
- </relocation>
  <relocation>
  <!-- relocate jackson services, which isn't done by flink-shaded-jackson -->
  <pattern>com.fasterxml.jackson</pattern>