code: public void setExpressionNames(java.util.Collection<String> expressionNames) {
          if (expressionNames == null) {
              this.expressionNames = null;
              return;
          }
  
          this.expressionNames = new com.amazonaws.internal.SdkInternalList<String>(expressionNames);
      }
docs: <p>
  Limits the <code><a>DescribeExpressions</a></code> response to the specified expressions. If not specified, all
  expressions are shown.
  </p>
  
  @param expressionNames
  Limits the <code><a>DescribeExpressions</a></code> response to the specified expressions. If not
  specified, all expressions are shown.