Java-API: Fix minor Javadoc copy-paste errors (#8034)

Summary:
Fixes 3 minor Javadoc copy-paste errors in the `RocksDB#newIterator()` and `Transaction#getIterator()` variants that take a column family handle but are talking about iterating over "the database" or "the default column family".

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8034

Reviewed By: jay-zhuang

Differential Revision: D26877667

Pulled By: mrambacher

fbshipit-source-id: 95dd95b667c496e389f221acc9a91b340e4b63bf

java/src/main/java/org/rocksdb/RocksDB.java

@@ -2834,8 +2834,8 @@ public class RocksDB extends RocksObject {
   }
 
   /**
-   * <p>Return a heap-allocated iterator over the contents of the
-   * database. The result of newIterator() is initially invalid
+   * <p>Return a heap-allocated iterator over the contents of a
+   * ColumnFamily. The result of newIterator() is initially invalid
    * (caller must call one of the Seek methods on the iterator
    * before using it).</p>
    *
@@ -2854,8 +2854,8 @@ public class RocksDB extends RocksObject {
   }
 
   /**
-   * <p>Return a heap-allocated iterator over the contents of the
-   * database. The result of newIterator() is initially invalid
+   * <p>Return a heap-allocated iterator over the contents of a
+   * ColumnFamily. The result of newIterator() is initially invalid
    * (caller must call one of the Seek methods on the iterator
    * before using it).</p>
    *

java/src/main/java/org/rocksdb/Transaction.java

@@ -611,9 +611,9 @@ public class Transaction extends RocksObject {
   }
 
   /**
-   * Returns an iterator that will iterate on all keys in the default
-   * column family including both keys in the DB and uncommitted keys in this
-   * transaction.
+   * Returns an iterator that will iterate on all keys in the column family
+   * specified by {@code columnFamilyHandle} including both keys in the DB
+   * and uncommitted keys in this transaction.
    *
    * Setting {@link ReadOptions#setSnapshot(Snapshot)} will affect what is read
    * from the DB but will NOT change which keys are read from this transaction