chore: Add Apache License header to cache-related Java files

Author: darkmatter18

connector/src/main/java/com/datastax/oss/cdc/cache/InMemoryCache.java

@@ -1,3 +1,18 @@
+/**
+ * Copyright DataStax, Inc 2021.
+ *
+ * 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 com.datastax.oss.cdc.cache;
 
 import com.github.benmanes.caffeine.cache.Cache;

connector/src/main/java/com/datastax/oss/cdc/cache/MutationCache.java

@@ -1,3 +1,18 @@
+/**
+ * Copyright DataStax, Inc 2021.
+ *
+ * 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 com.datastax.oss.cdc.cache;
 
 import com.github.benmanes.caffeine.cache.stats.CacheStats;

connector/src/main/java/com/datastax/oss/cdc/cache/PersistentCache.java

@@ -1,10 +1,24 @@
+/**
+ * Copyright DataStax, Inc 2021.
+ *
+ * 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 com.datastax.oss.cdc.cache;
 
 import com.github.benmanes.caffeine.cache.Cache;
 import com.github.benmanes.caffeine.cache.Caffeine;
 import com.github.benmanes.caffeine.cache.RemovalCause;
 import com.github.benmanes.caffeine.cache.stats.CacheStats;
-import com.google.common.annotations.VisibleForTesting;
 import org.rocksdb.Options;
 import org.rocksdb.RocksDBException;
 import org.rocksdb.TtlDB;