code: public DescribeExpressionsRequest withExpressionNames(String... expressionNames) {
          if (this.expressionNames == null) {
              setExpressionNames(new com.amazonaws.internal.SdkInternalList<String>(expressionNames.length));
          }
          for (String ele : expressionNames) {
              this.expressionNames.add(ele);
          }
          return this;
      }
docs: <p>
  Limits the <code><a>DescribeExpressions</a></code> response to the specified expressions. If not specified, all
  expressions are shown.
  </p>
  <p>
  <b>NOTE:</b> This method appends the values to the existing list (if any). Use
  {@link #setExpressionNames(java.util.Collection)} or {@link #withExpressionNames(java.util.Collection)} if you
  want to override the existing values.
  </p>
  
  @param expressionNames
  Limits the <code><a>DescribeExpressions</a></code> response to the specified expressions. If not
  specified, all expressions are shown.
  @return Returns a reference to this object so that method calls can be chained together.