public int getConstantValueIndex() {
		return constantValueIndex & 0xffff;
	}
The value of the constantvalue_index item must be a valid index into
the constant_pool table. The constant_pool entry at that index gives the
constant value represented by this attribute. The constant_pool entry must be
of a type appropriate to the field, as shown by Table 4.22.
<pre>
Table 4.22. Constant value attribute types
--------------------------------------------------
Field Type 						Entry Type
--------------------------------------------------
long								CONSTANT_Long
float							CONSTANT_Float
double							CONSTANT_Double
int, short, char, byte, boolean	CONSTANT_Integer
String							CONSTANT_String
--------------------------------------------------
</pre>
@return a valid index into the constant_pool table
Ghidra/Processors/JVM/src/main/java/ghidra/javaclass/format/attributes/ConstantValueAttribute.java