public int getTypeNameIndex() {
		if (tag != DescriptorDecoder.BASE_TYPE_ENUM) {
			throw new IllegalArgumentException();
		}
		return typeNameIndex & 0xffff;
	}
The value of the type_name_index item must be a valid index into
the constant_pool table. The constant_pool entry at that index
must be a CONSTANT_Utf8_info (?4.4.7) structure representing a valid
field descriptor (?4.3.2) that denotes the internal form of the binary
name (?4.2.1) of the type of the enum constant represented by this
element_value structure.
@return a valid index into the constant_pool table
Ghidra/Processors/JVM/src/main/java/ghidra/javaclass/format/attributes/AnnotationElementValue.java