types/src/main/java/com/google/common/html/types/SafeHtmlBuilder.java
public SafeHtmlBuilder setFormmethod(String value) {
    if (!FORMMETHOD_STRING_ELEMENT_WHITELIST.contains(elementName)) {
      throw new IllegalArgumentException(
          "Attribute \"formmethod\" with a String value can only be used "
              + "by one of the following elements: "
              + FORMMETHOD_STRING_ELEMENT_WHITELIST);
    }
    return setAttribute("formmethod", value);
  }
public SafeHtmlBuilder setFormmethod(String value) {
    if (!FORMMETHOD_STRING_ELEMENT_WHITELIST.contains(elementName)) {
      throw new IllegalArgumentException(
          "Attribute \"formmethod\" with a String value can only be used "
              + "by one of the following elements: "
              + FORMMETHOD_STRING_ELEMENT_WHITELIST);
    }
    return setAttribute("formmethod", value);
  }
Sets the {@code formmethod} attribute for this element.

<p>The attribute {@code formmethod} with a {@code String} value is allowed on these elements:

<ul>
<li>{@code button}
<li>{@code input}
</ul>

@throws IllegalArgumentException if the {@code formmethod} attribute with a {@code String}
value is not allowed on this element