Example of Hickory generating a prism for JPA column

ColumnPrism.java

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import javax.lang.model.element.AnnotationMirror;
import javax.lang.model.element.Element;
import javax.lang.model.element.VariableElement;
import javax.lang.model.element.AnnotationValue;
import javax.lang.model.type.TypeMirror;
import net.java.dev.hickory.prism.internal.*;
import java.util.HashMap;
import javax.lang.model.element.ExecutableElement;
import javax.lang.model.element.TypeElement;
import javax.lang.model.util.ElementFilter;
/** A Prism representing an {@code @javax.persistence.Column} annotation. 
  */ 
public class ColumnPrism {
    /** store prism value of columnDefinition */
    private String _columnDefinition;

    /** store prism value of insertable */
    private Boolean _insertable;

    /** store prism value of length */
    private Integer _length;

    /** store prism value of name */
    private String _name;

    /** store prism value of nullable */
    private Boolean _nullable;

    /** store prism value of precision */
    private Integer _precision;

    /** store prism value of scale */
    private Integer _scale;

    /** store prism value of table */
    private String _table;

    /** store prism value of unique */
    private Boolean _unique;

    /** store prism value of updatable */
    private Boolean _updatable;

    /**
      * An instance of the Values inner class whose
      * methods return the AnnotationValues used to build this prism. 
      * Primarily intended to support using Messager.
      */
    public final Values values;
    /** Return a prism representing the {@code @javax.persistence.Column} annotation on 'e'. 
      * similar to {@code e.getAnnotation(javax.persistence.Column.class)} except that 
      * an instance of this class rather than an instance of {@code javax.persistence.Column}
      * is returned.
      */
    public static ColumnPrism getInstanceOn(Element e) {
        AnnotationMirror m = getMirror("javax.persistence.Column",e);
        if(m == null) return null;
        return getInstance(m);
   }

    /** Return a prism of the {@code @javax.persistence.Column} annotation whose mirror is mirror. 
      */
    public static ColumnPrism getInstance(AnnotationMirror mirror) {
        return new ColumnPrism(mirror);
    }

    private ColumnPrism(AnnotationMirror mirror) {
        for(ExecutableElement key : mirror.getElementValues().keySet()) {
            memberValues.put(key.getSimpleName().toString(),mirror.getElementValues().get(key));
        }
        for(ExecutableElement member : ElementFilter.methodsIn(mirror.getAnnotationType().asElement().getEnclosedElements())) {
            defaults.put(member.getSimpleName().toString(),member.getDefaultValue());
        }
        _columnDefinition = getValue("columnDefinition",String.class);
        _insertable = getValue("insertable",Boolean.class);
        _length = getValue("length",Integer.class);
        _name = getValue("name",String.class);
        _nullable = getValue("nullable",Boolean.class);
        _precision = getValue("precision",Integer.class);
        _scale = getValue("scale",Integer.class);
        _table = getValue("table",String.class);
        _unique = getValue("unique",Boolean.class);
        _updatable = getValue("updatable",Boolean.class);
        this.values = new Values(memberValues);
        this.mirror = mirror;
        this.isValid = valid;
    }

    /** 
      * Returns a String representing the value of the {@code java.lang.String public abstract java.lang.String columnDefinition() } member of the Annotation.
      * @see javax.persistence.Column#columnDefinition()
      */ 
    public String columnDefinition() { return _columnDefinition; }

    /** 
      * Returns a Boolean representing the value of the {@code boolean public abstract boolean insertable() } member of the Annotation.
      * @see javax.persistence.Column#insertable()
      */ 
    public Boolean insertable() { return _insertable; }

    /** 
      * Returns a Integer representing the value of the {@code int public abstract int length() } member of the Annotation.
      * @see javax.persistence.Column#length()
      */ 
    public Integer length() { return _length; }

    /** 
      * Returns a String representing the value of the {@code java.lang.String public abstract java.lang.String name() } member of the Annotation.
      * @see javax.persistence.Column#name()
      */ 
    public String name() { return _name; }

    /** 
      * Returns a Boolean representing the value of the {@code boolean public abstract boolean nullable() } member of the Annotation.
      * @see javax.persistence.Column#nullable()
      */ 
    public Boolean nullable() { return _nullable; }

    /** 
      * Returns a Integer representing the value of the {@code int public abstract int precision() } member of the Annotation.
      * @see javax.persistence.Column#precision()
      */ 
    public Integer precision() { return _precision; }

    /** 
      * Returns a Integer representing the value of the {@code int public abstract int scale() } member of the Annotation.
      * @see javax.persistence.Column#scale()
      */ 
    public Integer scale() { return _scale; }

    /** 
      * Returns a String representing the value of the {@code java.lang.String public abstract java.lang.String table() } member of the Annotation.
      * @see javax.persistence.Column#table()
      */ 
    public String table() { return _table; }

    /** 
      * Returns a Boolean representing the value of the {@code boolean public abstract boolean unique() } member of the Annotation.
      * @see javax.persistence.Column#unique()
      */ 
    public Boolean unique() { return _unique; }

    /** 
      * Returns a Boolean representing the value of the {@code boolean public abstract boolean updatable() } member of the Annotation.
      * @see javax.persistence.Column#updatable()
      */ 
    public Boolean updatable() { return _updatable; }

    /**
      * Determine whether the underlying AnnotationMirror has no errors.
      * True if the underlying AnnotationMirror has no errors.
      * When true is returned, none of the methods will return null.
      * When false is returned, a least one member will either return null, or another
      * prism that is not valid.
      */
    public final boolean isValid;
    
    /**
      * The underlying AnnotationMirror of the annotation
      * represented by this Prism. 
      * Primarily intended to support using Messager.
      */
    public final AnnotationMirror mirror;
    /**
      * A class whose members corespond to those of javax.persistence.Column
      * but which each return the AnnotationValue corresponding to
      * that member in the model of the annotations. Returns null for
      * defaulted members. Used for Messager, so default values are not useful.
      */
    public static class Values {
       private Map<String,AnnotationValue> values;
       private Values(Map<String,AnnotationValue> values) {
           this.values = values;
       }    
       /** Return the AnnotationValue corresponding to the columnDefinition() 
         * member of the annotation, or null when the default value is implied.
         */
       public AnnotationValue columnDefinition(){ return values.get("columnDefinition");}
       /** Return the AnnotationValue corresponding to the insertable() 
         * member of the annotation, or null when the default value is implied.
         */
       public AnnotationValue insertable(){ return values.get("insertable");}
       /** Return the AnnotationValue corresponding to the length() 
         * member of the annotation, or null when the default value is implied.
         */
       public AnnotationValue length(){ return values.get("length");}
       /** Return the AnnotationValue corresponding to the name() 
         * member of the annotation, or null when the default value is implied.
         */
       public AnnotationValue name(){ return values.get("name");}
       /** Return the AnnotationValue corresponding to the nullable() 
         * member of the annotation, or null when the default value is implied.
         */
       public AnnotationValue nullable(){ return values.get("nullable");}
       /** Return the AnnotationValue corresponding to the precision() 
         * member of the annotation, or null when the default value is implied.
         */
       public AnnotationValue precision(){ return values.get("precision");}
       /** Return the AnnotationValue corresponding to the scale() 
         * member of the annotation, or null when the default value is implied.
         */
       public AnnotationValue scale(){ return values.get("scale");}
       /** Return the AnnotationValue corresponding to the table() 
         * member of the annotation, or null when the default value is implied.
         */
       public AnnotationValue table(){ return values.get("table");}
       /** Return the AnnotationValue corresponding to the unique() 
         * member of the annotation, or null when the default value is implied.
         */
       public AnnotationValue unique(){ return values.get("unique");}
       /** Return the AnnotationValue corresponding to the updatable() 
         * member of the annotation, or null when the default value is implied.
         */
       public AnnotationValue updatable(){ return values.get("updatable");}
    }
    private Map<String,AnnotationValue> defaults = new HashMap<String,AnnotationValue>(10);
    private Map<String,AnnotationValue> memberValues = new HashMap<String,AnnotationValue>(10);
    private boolean valid = true;

    private <T> T getValue(String name, Class<T> clazz) {
        T result = ColumnPrism.getValue(memberValues,defaults,name,clazz);
        if(result == null) valid = false;
        return result;
    } 

    private <T> List<T> getArrayValues(String name, final Class<T> clazz) {
        List<T> result = ColumnPrism.getArrayValues(memberValues,defaults,name,clazz);
        if(result == null) valid = false;
        return result;
    }
    private static AnnotationMirror getMirror(String fqn, Element target) {
        for (AnnotationMirror m :target.getAnnotationMirrors()) {
            CharSequence mfqn = ((TypeElement)m.getAnnotationType().asElement()).getQualifiedName();
            if(fqn.contentEquals(mfqn)) return m;
        }
        return null;
    }
    private static <T> T getValue(Map<String,AnnotationValue> memberValues, Map<String,AnnotationValue> defaults, String name, Class<T> clazz) {
        AnnotationValue av = memberValues.get(name);
        if(av == null) av = defaults.get(name);
        if(av == null) {
            return null;
        }
        if(clazz.isInstance(av.getValue())) return clazz.cast(av.getValue());
        return null;
    }
    private static <T> List<T> getArrayValues(Map<String,AnnotationValue> memberValues, Map<String,AnnotationValue> defaults, String name, final Class<T> clazz) {
        AnnotationValue av = memberValues.get(name);
        if(av == null) av = defaults.get(name);
        if(av == null) {
            return null;
        }
        if(av.getValue() instanceof List) {
            List<T> result = new ArrayList<T>();
            for(AnnotationValue v : getValueAsList(av)) {
                if(clazz.isInstance(v.getValue())) {
                    result.add(clazz.cast(v.getValue()));
                } else{
                    return null;
                }
            }
            return result;
        } else {
            return null;
        }
    }
    @SuppressWarnings("unchecked")
    private static List<AnnotationValue> getValueAsList(AnnotationValue av) {
        return (List<AnnotationValue>)av.getValue();
    }
}

Hickory's doc:

https://www.mvndoc.com/c/com.jolira/hickory/index.html

    <dependency>
      <groupId>com.jolira</groupId>
      <artifactId>hickory</artifactId>
      <version>1.0.0</version>
      <scope>provided</scope>
      <optional>true</optional>
    </dependency>

    <dependency>
      <groupId>org.hibernate.javax.persistence</groupId>
      <artifactId>hibernate-jpa-2.1-api</artifactId>
      <version>1.0.0.Final</version>
      <scope>provided</scope>
      <optional>true</optional>
    </dependency>