### Question:
SpannerConnectionConfiguration { public int getThreadPoolSize() { return this.threadPoolSize; } private  SpannerConnectionConfiguration(String url, GoogleCredentials credentials); private  SpannerConnectionConfiguration(
      String projectId,
      String instanceName,
      String databaseName,
      GoogleCredentials credentials); String getProjectId(); String getInstanceName(); String getDatabaseName(); String getFullyQualifiedDatabaseName(); GoogleCredentials getCredentials(); int getPartialResultSetFetchSize(); Duration getDdlOperationTimeout(); Duration getDdlOperationPollInterval(); int getThreadPoolSize(); @Override boolean equals(Object o); @Override int hashCode();  }### Answer:
@Test public void executorThreads() { SpannerConnectionConfiguration config = this.configurationBuilder .setThreadPoolSize(42) .setProjectId("project1") .setInstanceName("an-instance") .setDatabaseName("db") .build(); assertThat(config.getThreadPoolSize()).isEqualTo(42); }
@Test public void executorThreadsNotSet() { SpannerConnectionConfiguration config = this.configurationBuilder .setProjectId("project1") .setInstanceName("an-instance") .setDatabaseName("db") .build(); assertThat(config.getThreadPoolSize()) .isEqualTo(Runtime.getRuntime().availableProcessors()); }