assertNull(Strings.emptyToNull(""));
    assertEquals("a", Strings.emptyToNull("a"));
  }

  public void testIsNullOrEmpty() {
    assertTrue(Strings.isNullOrEmpty(null));
    assertTrue(Strings.isNullOrEmpty(""));
    assertFalse(Strings.isNullOrEmpty("a"));
  }

  public void testPadStart_noPadding() {
    assertSame("", Strings.padStart("", 0, '-'));
    assertSame("x", Strings.padStart("x", 0, '-'));

                deferred.reject(new SuggesterException(e.getMessage(), e));
            }
        });
    }

    private boolean isSingleWordQuery(final String query) {
        return !Strings.isNullOrEmpty(query) && !query.contains(" ") && !query.contains("　");
    }

    /**
     * Builds the query for suggestions.
     * @param q The query string.
     * @param fields The fields to search in.

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import static com.google.common.base.Strings.isNullOrEmpty;
import static com.google.common.collect.Iterables.concat;
import static com.google.common.collect.Lists.newArrayList;
import static com.google.common.truth.Truth.assertThat;
import static java.util.Collections.nCopies;

internal fun <T> immutableListOf(vararg elements: T): List<T> = elements.toImmutableList()

/** Returns an immutable list from copy of this. */
internal fun <T> Array<out T>?.toImmutableList(): List<T> =
  when {
    this.isNullOrEmpty() -> emptyList()
    this.size == 1 -> Collections.singletonList(this[0])
    else -> this.clone().asList().unmodifiable()
  }

/** Closes this, ignoring any checked exceptions. */

   *
   * @param string a string reference to check
   * @return {@code true} if the string is null or is the empty string
   */
  public static boolean isNullOrEmpty(@Nullable String string) {
    return Platform.stringIsNullOrEmpty(string);
  }

  /**
   * Returns a string, of length at least {@code minLength}, consisting of {@code string} prepended