Use string concatenation in QueryExtractorDelegate instead of String.format(…).

We now use string concatenation during query extraction to avoid String.format(…) overhead for unknown queries.

Closes #1186

Author: mp911de

spring-data-cassandra/src/main/java/org/springframework/data/cassandra/core/cql/QueryExtractorDelegate.java

@@ -15,15 +15,16 @@
  */
 package org.springframework.data.cassandra.core.cql;
 
-import org.springframework.lang.Nullable;
-
 import com.datastax.oss.driver.api.core.cql.BatchStatement;
 import com.datastax.oss.driver.api.core.cql.BatchableStatement;
 import com.datastax.oss.driver.api.core.cql.BoundStatement;
 import com.datastax.oss.driver.api.core.cql.PreparedStatement;
 import com.datastax.oss.driver.api.core.cql.SimpleStatement;
 import com.datastax.oss.driver.api.core.cql.Statement;
 
+import org.springframework.lang.Nullable;
+import org.springframework.util.ObjectUtils;
+
 /**
  * Utility to extract CQL queries from a {@link Statement}.
  *
@@ -68,12 +69,16 @@ public static String getCql(@Nullable Object statement) {
 			for (BatchableStatement<?> batchableStatement : ((BatchStatement) statement)) {
 
 				String query = getCql(batchableStatement);
-				builder.append(query).append(query.endsWith(";") ? "" : ";");
+				builder.append(query);
+
+				if (!ObjectUtils.isEmpty(query)) {
+					builder.append(query.endsWith(";") ? "" : ";");
+				}
 			}
 
 			return builder.toString();
 		}
 
-		return String.format("Unknown: %s", statement);
+		return "Unknown: " + statement;
 	}
 }