[HUDI-4223] Fix NullPointerException from getLogRecordScanner when reading metadata table (apache#5840)

When explicitly specifying the metadata table path for reading in spark, the "hoodie.metadata.enable" is overwritten to true for proper read behavior.

Author: yihua

hudi-spark-datasource/hudi-spark-common/src/main/scala/org/apache/hudi/HoodieMergeOnReadRDD.scala

@@ -25,7 +25,6 @@ import org.apache.hadoop.fs.Path
 import org.apache.hadoop.mapred.JobConf
 import org.apache.hudi.HoodieConversionUtils.{toJavaOption, toScalaOption}
 import org.apache.hudi.HoodieMergeOnReadRDD.{AvroDeserializerSupport, collectFieldOrdinals, getPartitionPath, projectAvro, projectAvroUnsafe, projectRowUnsafe, resolveAvroSchemaNullability}
-import org.apache.hudi.MergeOnReadSnapshotRelation.getFilePath
 import org.apache.hudi.common.config.HoodieMetadataConfig
 import org.apache.hudi.common.engine.HoodieLocalEngineContext
 import org.apache.hudi.common.fs.FSUtils
@@ -37,9 +36,9 @@ import org.apache.hudi.config.HoodiePayloadConfig
 import org.apache.hudi.exception.HoodieException
 import org.apache.hudi.hadoop.config.HoodieRealtimeConfig
 import org.apache.hudi.hadoop.utils.HoodieRealtimeRecordReaderUtils.getMaxCompactionMemoryInBytes
+import org.apache.hudi.internal.schema.InternalSchema
 import org.apache.hudi.metadata.HoodieTableMetadata.getDataTableBasePathFromMetadataTable
 import org.apache.hudi.metadata.{HoodieBackedTableMetadata, HoodieTableMetadata}
-import org.apache.hudi.internal.schema.InternalSchema
 import org.apache.spark.rdd.RDD
 import org.apache.spark.sql.avro.HoodieAvroDeserializer
 import org.apache.spark.sql.catalyst.InternalRow
@@ -324,7 +323,8 @@ private object HoodieMergeOnReadRDD {
     val fs = FSUtils.getFs(tablePath, hadoopConf)
 
     if (HoodieTableMetadata.isMetadataTable(tablePath)) {
-      val metadataConfig = tableState.metadataConfig
+      val metadataConfig = HoodieMetadataConfig.newBuilder()
+        .fromProperties(tableState.metadataConfig.getProps).enable(true).build()
       val dataTableBasePath = getDataTableBasePathFromMetadataTable(tablePath)
       val metadataTable = new HoodieBackedTableMetadata(
         new HoodieLocalEngineContext(hadoopConf), metadataConfig,

hudi-spark-datasource/hudi-spark/src/test/scala/org/apache/hudi/functional/TestMetadataTableWithSparkDataSource.scala

@@ -78,7 +78,7 @@ class TestMetadataTableWithSparkDataSource extends SparkClientFunctionalTestHarn
       .save(basePath)
 
     // Files partition of MT
-    val filesPartitionDF = spark.read.options(metadataOpts).format(hudi).load(s"$basePath/.hoodie/metadata/files")
+    val filesPartitionDF = spark.read.format(hudi).load(s"$basePath/.hoodie/metadata/files")
 
     // Smoke test
     filesPartitionDF.show()
@@ -96,7 +96,7 @@ class TestMetadataTableWithSparkDataSource extends SparkClientFunctionalTestHarn
     assertEquals(expectedKeys, keys)
 
     // Column Stats Index partition of MT
-    val colStatsDF = spark.read.options(metadataOpts).format(hudi).load(s"$basePath/.hoodie/metadata/column_stats")
+    val colStatsDF = spark.read.format(hudi).load(s"$basePath/.hoodie/metadata/column_stats")
 
     // Smoke test
     colStatsDF.show()