public String getFile(
     String appName, int instanceIndex, String filePath, int startPosition, int endPosition) {
   Assert.isTrue(
       startPosition >= 0,
       startPosition + " is not a valid value for start position, it should be 0 or greater.");
   Assert.isTrue(
       endPosition > startPosition,
       endPosition
           + " is not a valid value for end position, it should be greater than startPosition "
           + "which is "
           + startPosition
           + ".");
   return cc.getFile(appName, instanceIndex, filePath, startPosition, endPosition - 1);
 }
 public String getFileTail(String appName, int instanceIndex, String filePath, int length) {
   Assert.isTrue(
       length > 0, length + " is not a valid value for length, it should be 1 or greater.");
   return cc.getFile(appName, instanceIndex, filePath, -1, length);
 }
 public String getFile(String appName, int instanceIndex, String filePath, int startPosition) {
   Assert.isTrue(
       startPosition >= 0,
       startPosition + " is not a valid value for start position, it should be 0 or greater.");
   return cc.getFile(appName, instanceIndex, filePath, startPosition, -1);
 }
 public String getFile(String appName, int instanceIndex, String filePath) {
   return cc.getFile(appName, instanceIndex, filePath, 0, -1);
 }