Remove unused imports

Because of some of the corrections made to resolve issues that ErrorProne identified, some of the old imports are no longer valid.

spring-batch-core/src/main/java/org/springframework/batch/core/JobExecution.java

@@ -18,7 +18,6 @@ package org.springframework.batch.core;
 
 import java.io.IOException;
 import java.io.ObjectInputStream;
-import java.time.Clock;
 import java.time.LocalDateTime;
 import java.util.ArrayList;
 import java.util.Collection;

spring-batch-core/src/main/java/org/springframework/batch/core/configuration/support/AbstractApplicationContextFactory.java

@@ -19,7 +19,6 @@ package org.springframework.batch.core.configuration.support;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.List;
 
 import org.apache.commons.logging.Log;

spring-batch-core/src/test/java/org/springframework/batch/core/listener/MulticasterBatchListenerTests.java

@@ -18,7 +18,6 @@ package org.springframework.batch.core.listener;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertInstanceOf;
 import static org.junit.jupiter.api.Assertions.assertThrows;
-import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.util.Arrays;
 

spring-batch-core/src/test/java/org/springframework/batch/core/repository/support/SimpleJobRepositoryTests.java

@@ -20,7 +20,6 @@ import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
-import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/file/SimpleBinaryBufferedReaderFactory.java

@@ -19,7 +19,6 @@ import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.io.Reader;
-import java.io.UnsupportedEncodingException;
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReentrantLock;