Retain regex options from the parsed JsonToken.

We now retain expression options when resolving bind values from the original BsonRegularExpression.

Closes: #4806
Original Pull Request: #4807

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/util/json/ParameterBindingJsonReader.java

@@ -456,7 +456,9 @@ public class ParameterBindingJsonReader extends AbstractBsonReader {
 
 		if (isRegularExpression) {
 
-			bindableValue.setValue(new BsonRegularExpression(computedValue));
+			BsonRegularExpression originalExpression = token.getValue(BsonRegularExpression.class);
+
+			bindableValue.setValue(new BsonRegularExpression(computedValue, originalExpression.getOptions()));
 			bindableValue.setType(BsonType.REGULAR_EXPRESSION);
 		} else {
 

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/util/json/ParameterBindingJsonReaderUnitTests.java

@@ -26,6 +26,7 @@ import java.util.UUID;
 
 import org.bson.BsonBinary;
 import org.bson.BsonBinarySubType;
+import org.bson.BsonRegularExpression;
 import org.bson.Document;
 import org.bson.codecs.DecoderContext;
 import org.junit.jupiter.api.Test;
@@ -81,6 +82,26 @@ class ParameterBindingJsonReaderUnitTests {
 		assertThat(target).isEqualTo(new Document("lastname", "100"));
 	}
 
+	@Test // GH-4806
+	void regexConsidersOptions() {
+
+		Document target = parse("{ 'c': /^true$/i }");
+
+		BsonRegularExpression pattern = target.get("c", BsonRegularExpression.class);
+		assertThat(pattern.getPattern()).isEqualTo("^true$");
+		assertThat(pattern.getOptions()).isEqualTo("i");
+	}
+
+	@Test // GH-4806
+	void regexConsidersBindValueWithOptions() {
+
+		Document target = parse("{ 'c': /^?0$/i }", "foo");
+
+		BsonRegularExpression pattern = target.get("c", BsonRegularExpression.class);
+		assertThat(pattern.getPattern()).isEqualTo("^foo$");
+		assertThat(pattern.getOptions()).isEqualTo("i");
+	}
+
 	@Test
 	void bindValueToRegex() {