Remove unused Clock.

api/src/main/java/openconsensus/common/Clock.java

@@ -1,43 +0,0 @@
-/*
- * Copyright 2019, OpenConsensus Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package openconsensus.common;
-
-/**
- * Interface for getting the current time.
- *
- * @since 0.1.0
- */
-public abstract class Clock {
-
-  /**
-   * Obtains the current instant from this clock.
-   *
-   * @return the current instant.
-   * @since 0.1.0
-   */
-  public abstract Timestamp now();
-
-  /**
-   * Returns a time measurement with nanosecond precision that can only be used to calculate elapsed
-   * time.
-   *
-   * @return a time measurement with nanosecond precision that can only be used to calculate elapsed
-   *     time.
-   * @since 0.1.0
-   */
-  public abstract long nowNanos();
-}

api/src/main/java/openconsensus/internal/ZeroTimeClock.java

@@ -1,49 +0,0 @@
-/*
- * Copyright 2019, OpenConsensus Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package openconsensus.internal;
-
-import javax.annotation.concurrent.Immutable;
-import openconsensus.common.Clock;
-import openconsensus.common.Timestamp;
-
-/** A {@link Clock} that always returns 0. */
-@Immutable
-public final class ZeroTimeClock extends Clock {
-  private static final ZeroTimeClock INSTANCE = new ZeroTimeClock();
-  private static final Timestamp ZERO_TIMESTAMP = Timestamp.create(0, 0);
-
-  private ZeroTimeClock() {}
-
-  /**
-   * Returns a {@code ZeroTimeClock}.
-   *
-   * @return a {@code ZeroTimeClock}.
-   */
-  public static ZeroTimeClock getInstance() {
-    return INSTANCE;
-  }
-
-  @Override
-  public Timestamp now() {
-    return ZERO_TIMESTAMP;
-  }
-
-  @Override
-  public long nowNanos() {
-    return 0;
-  }
-}