ParseSpec: Remove default setting. (#6310)

* ParseSpec: Remove default setting.

Having a default ParseSpec implementation is bad for users, because it masks
problems specifying the format. Two common problems masked by this are specifying
the "format" at the wrong level of the JSON, and specifying a format that
Druid doesn't support. In both cases, having a default implementation means that
users will get the delimited parser rather than an error, and then be confused
when, later on, their data failed to parse.

* Fix integration tests.

api/src/main/java/org/apache/druid/data/input/impl/ParseSpec.java

@@ -30,7 +30,7 @@ import org.apache.druid.java.util.common.parsers.Parser;
 import java.util.List;
 
 @ExtensionPoint
-@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "format", defaultImpl = DelimitedParseSpec.class)
+@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "format")
 @JsonSubTypes(value = {
     @JsonSubTypes.Type(name = "json", value = JSONParseSpec.class),
     @JsonSubTypes.Type(name = "csv", value = CSVParseSpec.class),

api/src/test/java/org/apache/druid/data/input/impl/ParseSpecTest.java

@@ -19,12 +19,22 @@
 
 package org.apache.druid.data.input.impl;
 
+import com.fasterxml.jackson.databind.DeserializationFeature;
+import com.fasterxml.jackson.databind.JsonMappingException;
+import com.fasterxml.jackson.databind.MapperFeature;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Lists;
+import org.apache.druid.java.util.common.jackson.JacksonUtils;
 import org.apache.druid.java.util.common.parsers.ParseException;
+import org.hamcrest.CoreMatchers;
+import org.junit.Assert;
+import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
 
+import java.io.IOException;
 import java.util.Arrays;
 import java.util.Collections;
 
@@ -33,6 +43,21 @@ public class ParseSpecTest
   @Rule
   public ExpectedException expectedException = ExpectedException.none();
 
+  private ObjectMapper mapper;
+
+  @Before
+  public void setUp()
+  {
+    // Similar to configs from DefaultObjectMapper, which we cannot use here since we're in druid-api.
+    mapper = new ObjectMapper();
+    mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
+    mapper.configure(MapperFeature.AUTO_DETECT_GETTERS, false);
+    mapper.configure(MapperFeature.AUTO_DETECT_FIELDS, false);
+    mapper.configure(MapperFeature.AUTO_DETECT_IS_GETTERS, false);
+    mapper.configure(MapperFeature.AUTO_DETECT_SETTERS, false);
+    mapper.configure(MapperFeature.ALLOW_FINAL_FIELDS_AS_MUTATORS, false);
+  }
+
   @Test(expected = ParseException.class)
   public void testDuplicateNames()
   {
@@ -143,4 +168,44 @@ public class ParseSpecTest
         0
     );
   }
+
+  @Test
+  public void testSerde() throws IOException
+  {
+    final String json = "{"
+                        + "\"format\":\"timeAndDims\", "
+                        + "\"timestampSpec\": {\"column\":\"timestamp\"}, "
+                        + "\"dimensionsSpec\":{}"
+                        + "}";
+
+    final Object mapValue = mapper.readValue(json, JacksonUtils.TYPE_REFERENCE_MAP_STRING_OBJECT);
+    final ParseSpec parseSpec = mapper.convertValue(mapValue, ParseSpec.class);
+
+    Assert.assertEquals(TimeAndDimsParseSpec.class, parseSpec.getClass());
+    Assert.assertEquals("timestamp", parseSpec.getTimestampSpec().getTimestampColumn());
+    Assert.assertEquals(ImmutableList.of(), parseSpec.getDimensionsSpec().getDimensionNames());
+
+    // Test round-trip.
+    Assert.assertEquals(
+        parseSpec,
+        mapper.readValue(mapper.writeValueAsString(parseSpec), ParseSpec.class)
+    );
+  }
+
+  @Test
+  public void testBadTypeSerde() throws IOException
+  {
+    final String json = "{"
+                        + "\"format\":\"foo\", "
+                        + "\"timestampSpec\": {\"column\":\"timestamp\"}, "
+                        + "\"dimensionsSpec\":{}"
+                        + "}";
+
+    final Object mapValue = mapper.readValue(json, JacksonUtils.TYPE_REFERENCE_MAP_STRING_OBJECT);
+
+    expectedException.expect(IllegalArgumentException.class);
+    expectedException.expectCause(CoreMatchers.instanceOf(JsonMappingException.class));
+    expectedException.expectMessage("Could not resolve type id 'foo' into a subtype");
+    mapper.convertValue(mapValue, ParseSpec.class);
+  }
 }

integration-tests/src/test/resources/indexer/wikipedia_realtime_appenderator_index_task.json

@@ -31,6 +31,7 @@
       "parser": {
         "type": "map",
         "parseSpec": {
+          "format": "tsv",
           "columns": [
             "timestamp",
             "page",

integration-tests/src/test/resources/indexer/wikipedia_realtime_index_task.json

@@ -31,6 +31,7 @@
       "parser": {
         "type": "map",
         "parseSpec": {
+          "format": "tsv",
           "columns": [
             "timestamp",
             "page",

integration-tests/src/test/resources/indexer/wikipedia_union_index_task.json

@@ -31,6 +31,7 @@
       "parser": {
         "type": "map",
         "parseSpec": {
+          "format": "tsv",
           "columns": [
             "timestamp",
             "page",