fix(bigquery): support optional fields in BigLakeConfiguration to prevent NPE on Iceberg/Lakehouse tables (#13733)

b/534291682

This PR resolves a `NullPointerException` encountered when querying or
retrieving metadata for 4-part PCNT (Project.Catalog.Namespace.Table)
Apache Iceberg tables governed by external REST catalogs.

#### Changes
* Annotated all 4 fields (`connectionId`, `fileFormat`, `storageUri`,
`tableFormat`) and their corresponding setters in `@AutoValue.Builder`
with `@Nullable` in `BigLakeConfiguration.java`.
* Cleaned up the Javadoc comments for the builder setters in
`BigLakeConfiguration.java` to remove incorrect `[Required]` notations
and updated `getTableFormat()` Javadoc to reflect the correct table
format reference (e.g., Iceberg) instead of file format.
* Added unit test coverage to `BigLakeConfigurationTest.java`
(`testNullFields`, `testFromPbWithNullFields`) to verify that
constructing the configuration or mapping it from API models works
successfully when properties are null.

Author: keshavdandeva

java-bigquery/google-cloud-bigquery/src/main/java/com/google/cloud/bigquery/BigLakeConfiguration.java

@@ -18,6 +18,7 @@
 
 import com.google.auto.value.AutoValue;
 import java.io.Serializable;
+import org.jspecify.annotations.Nullable;
 
 @AutoValue
 public abstract class BigLakeConfiguration implements Serializable {
@@ -30,13 +31,15 @@ public abstract class BigLakeConfiguration implements Serializable {
    *
    * @return value or {@code null} for none
    */
+  @Nullable
   public abstract String getConnectionId();
 
   /**
    * Open source file format that the table data is stored in. Currently only PARQUET is supported.
    *
    * @return value or {@code null} for none
    */
+  @Nullable
   public abstract String getFileFormat();
 
   /**
@@ -45,13 +48,15 @@ public abstract class BigLakeConfiguration implements Serializable {
    *
    * @return value or {@code null} for none
    */
+  @Nullable
   public abstract String getStorageUri();
 
   /**
-   * Open source file format that the table data is stored in. Currently only PARQUET is supported.
+   * Open source table format that the table data is stored in. Currently only ICEBERG is supported.
    *
    * @return value or {@code null} for none
    */
+  @Nullable
   public abstract String getTableFormat();
 
   public static Builder newBuilder() {
@@ -63,36 +68,36 @@ public static Builder newBuilder() {
   @AutoValue.Builder
   public abstract static class Builder {
     /**
-     * [Required] Required and immutable. Credential reference for accessing external storage
-     * system. Normalized as project_id.location_id.connection_id.
+     * Credential reference for accessing external storage system. Normalized as
+     * project_id.location_id.connection_id.
      *
      * @param connectionId connectionId or {@code null} for none
      */
-    public abstract Builder setConnectionId(String connectionId);
+    public abstract Builder setConnectionId(@Nullable String connectionId);
 
     /**
-     * [Required] Required and immutable. Open source file format that the table data is stored in.
-     * Currently only PARQUET is supported.
+     * Open source file format that the table data is stored in. Currently only PARQUET is
+     * supported.
      *
      * @param fileFormat fileFormat or {@code null} for none
      */
-    public abstract Builder setFileFormat(String fileFormat);
+    public abstract Builder setFileFormat(@Nullable String fileFormat);
 
     /**
-     * [Required] Required and immutable. Fully qualified location prefix of the external folder
-     * where data is stored. Starts with "gs://" and ends with "/". Does not contain "*".
+     * Fully qualified location prefix of the external folder where data is stored. Starts with
+     * "gs://" and ends with "/". Does not contain "*".
      *
      * @param storageUri storageUri or {@code null} for none
      */
-    public abstract Builder setStorageUri(String storageUri);
+    public abstract Builder setStorageUri(@Nullable String storageUri);
 
     /**
-     * [Required] Required and immutable. Open source file format that the table data is stored in.
-     * Currently only PARQUET is supported.
+     * Open source table format that the table data is stored in. Currently only ICEBERG is
+     * supported.
      *
      * @param tableFormat tableFormat or {@code null} for none
      */
-    public abstract Builder setTableFormat(String tableFormat);
+    public abstract Builder setTableFormat(@Nullable String tableFormat);
 
     public abstract BigLakeConfiguration build();
   }

java-bigquery/google-cloud-bigquery/src/test/java/com/google/cloud/bigquery/BigLakeConfigurationTest.java

@@ -17,6 +17,7 @@
 package com.google.cloud.bigquery;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
 
 import org.junit.jupiter.api.Test;
 
@@ -61,6 +62,26 @@ void testFromPb() {
         BIG_LAKE_CONFIGURATION, BigLakeConfiguration.fromPb(BIG_LAKE_CONFIGURATION_PB));
   }
 
+  @Test
+  void testNullFields() {
+    BigLakeConfiguration configuration = BigLakeConfiguration.newBuilder().build();
+    assertNull(configuration.getConnectionId());
+    assertNull(configuration.getFileFormat());
+    assertNull(configuration.getStorageUri());
+    assertNull(configuration.getTableFormat());
+  }
+
+  @Test
+  void testFromPbWithNullFields() {
+    com.google.api.services.bigquery.model.BigLakeConfiguration pb =
+        new com.google.api.services.bigquery.model.BigLakeConfiguration();
+    BigLakeConfiguration configuration = BigLakeConfiguration.fromPb(pb);
+    assertNull(configuration.getConnectionId());
+    assertNull(configuration.getFileFormat());
+    assertNull(configuration.getStorageUri());
+    assertNull(configuration.getTableFormat());
+  }
+
   private static void assertBigLakeConfiguration(
       BigLakeConfiguration expected, BigLakeConfiguration actual) {
     assertEquals(expected.getConnectionId(), actual.getConnectionId());