fix: doc errors.

Author: arpan14

google-cloud-spanner/src/main/java/com/google/cloud/spanner/AbstractLazyInitializer.java

@@ -19,6 +19,8 @@
 /**
  * Generic {@link AbstractLazyInitializer} for any heavy-weight object that might throw an exception
  * during initialization. The underlying object is initialized at most once.
+ *
+ * @param <T> Object which is to be initialized lazily
  */
 public abstract class AbstractLazyInitializer<T> {
   private final Object lock = new Object();

google-cloud-spanner/src/main/java/com/google/cloud/spanner/AsyncTransactionManager.java

@@ -115,6 +115,9 @@ Timestamp get(long timeout, TimeUnit unit)
    *     executor)
    *   .commitAsync();
    * }</pre>
+   *
+   * @param <I>
+   * @param <O>
    */
   interface AsyncTransactionStep<I, O> extends ApiFuture<O> {
     /**
@@ -140,6 +143,9 @@ <RES> AsyncTransactionStep<O, RES> then(
    * a {@link TransactionContext} and the output value of the previous transaction step as its input
    * parameters. The method should return an {@link ApiFuture} that will return the result of this
    * step.
+   *
+   * @param <I>
+   * @param <O>
    */
   interface AsyncTransactionFunction<I, O> {
     /**

google-cloud-spanner/src/main/java/com/google/cloud/spanner/Operation.java

@@ -32,7 +32,12 @@
 import javax.annotation.Nullable;
 import org.threeten.bp.Duration;
 
-/** Represents a long running operation. */
+/**
+ * Represents a long-running operation.
+ *
+ * @param <R>
+ * @param <M>
+ */
 // TODO(user): Implement other operations on Operation.
 public class Operation<R, M> {
 

google-cloud-spanner/src/main/java/com/google/cloud/spanner/TransactionManager.java

@@ -17,6 +17,7 @@
 package com.google.cloud.spanner;
 
 import com.google.cloud.Timestamp;
+import com.google.cloud.spanner.Options.TransactionOption;
 
 /**
  * An interface for managing the life cycle of a read write transaction including all its retries.
@@ -33,7 +34,7 @@
  * can cause resources to be leaked and deadlocks. Easiest way to guarantee this is by calling
  * {@link #close()} in a finally block.
  *
- * @see DatabaseClient#transactionManager()
+ * @see DatabaseClient#transactionManager(TransactionOption...)
  */
 public interface TransactionManager extends AutoCloseable {
 

google-cloud-spanner/src/main/java/com/google/cloud/spanner/ValueBinder.java

@@ -31,6 +31,8 @@
  *
  * <p>{@code ValueBinder} subclasses typically carry state and are therefore not thread-safe,
  * although the core implementation itself is thread-safe.
+ *
+ * @param <R> The context which is used to bind the {@link Value}.
  */
 public abstract class ValueBinder<R> {
   /**